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As the international environment dissolves into pools of power swirling around the rise of China, India, and other regional powers, new and unfamiliar perils intrude—such as the world of Islam at war, terrorism with a global reach, and impending conflicts over food, water, and habitats driven by climate change. And as old political patterns, arrangements, and outlooks crumble, the world looks increasingly messy, without an identifiable political structure and without a clear sense of which forces of change will most shape the future. Will it be the turmoil of an unending series of regional conflicts? Or the “clash of civilizations” most furiously manifest in Islamist terrorism? Or the bill to be paid for the mounting social and economic inequalities within and between societies? Or a rogue actor, possibly a government, that sets off a nuclear conflagration? Or perhaps some combination of them all, or even forces unforeseen?

In the haze, however, another trend directly affecting key nuclear states has suddenly intruded. Great power strategic rivalry is resurgent again. In the last half decade, the U.S.-Russian relationship has sailed off the tracks and into a new Cold War.1 At the same time, in the delicate balance between cooperation and competition, U.S.-China relations, which were mixed before, are slowly tilting toward competition, giving rise to the possibility of military conflict between them. Inevitably, these changes impinge on the nuclear dimension of both relationships. They are starkest, for example, in the transfigured assumptions underlying an evolving U.S. nuclear posture. In 2010, with the positive effects of the “reset” in U.S.-Russian relations still being felt, the U.S. Nuclear Posture Review stressed working with Russia to enhance strategic stability and jointly to reduce the number and role of nuclear weapons because “Russia and the United States are no longer adversaries, and prospects for military confrontation have declined dramatically.”2 China, too, was treated as more a partner than an adversary, even though the lack of transparency in its nuclear plans remained a source of concern. “The United States and China,” as stated in the 2010 Nuclear Posture Review, “are increasingly interdependent and their shared responsibilities for addressing global security threats, such as weapons of mass destruction (WMD) proliferation and terrorism, are growing.”3

By 2018, the new Nuclear Posture Review painted a very different picture. There has been, it asserted, “a rapid deterioration of the threat environment since 2010,” a “return to great power competition,” with “potential adversaries,” in particular, Russia and China, “expand[ing] and moderniz[ing] their nuclear forces” in ways designed to degrade the U.S. nuclear deterrent and its ability to defend regional allies.4  Both countries, the document claims, have “made clear they seek to substantially revise the post–Cold War international order and norms of behavior.”5

A quarter century earlier the collapse of the Cold War bipolar order had fractured the structure of power, but in an asymmetrical fashion. During the Cold War, in narrow military terms, the United States and its allies worried first about a “bomber gap” in the mid-1950s and then a “missile gap” in the early 1960s. Yet throughout the initial post–Cold War period, Russia, in more profound respects, had confronted a “security gap.” The threats to its national security, both real and conjured, were more immediate, large, and diverse than anything felt by the United States or its European allies.

For the United States, favored by the discrepancy in economic and military power over all others, the world’s dangers were omnibus, complex, and new, but they were scarcely a mortal threat and, for the most part, remained distant. Nuclear weapons were treated as secondary and, in response to most threats, irrelevant. Their object had become more an abstraction—insurance against the unknown—than an identifiable adversary or adversaries.

Russia, in contrast, saw the challenges posed by the outside world as far larger, near at hand, and embodied in the distinct form of the power and policies of a major state and its alliance partners. In a setting in which threats arose out of the rubble of what was once its security glacis, mounted by states again viewed as potential adversaries—indeed, where the greatest sources of instability touch its borders—nuclear weapons assumed a far more prominent place, both as underpinning for the status it claimed and as makeweight for the deficiencies in the country’s conventional military resources.

China’s relationship to the larger setting was different. It was already a rising power, eyed with apprehension by neighboring powers, determined to have a prominent, perhaps dominant role within its region and a significant voice globally, and locked in a delicate and uncertain balance with the one power that remained its superior. As the asymmetrical weight of the United States and China in international politics shrank, the fundamental asymmetry in their nuclear capabilities added both uncertainty to the broad U.S.-China relationship and a new and potentially destabilizing dynamic to its nuclear component. Where before the nuclear factor had been consciously downplayed, leaving China, as its leaders wished, an afterthought in the high politics of the U.S.-Soviet nuclear contest, the role that it now sought and the challenges facing it, including from more than one nuclear power, inevitably heightened the significance of nuclear weapons in Chinese foreign policy. China mattered increasingly as not merely a global actor but as one with nuclear weapons.

In the case of India and Pakistan, their bilateral relationship was influenced less by the diffusion of power in a post–Cold War world than by the asymmetry in their rapidly growing conventional and nuclear forces. On the other hand, ���Ի徱��’s relationship with China and its nuclear dimension did reflect the rise of China in a piebald world, lengthening the shadow of their long-standing border conflicts and augmenting the effect of China’s global thrust, including into the Indian Ocean. At the same time, another reality was also taking shape. While academics argued over whether the post–Cold War international order was becoming unipolar, multipolar, uni-multipolar, or non-polar, among the nuclear-weapons-possessing states the geometry was also changing but more starkly.6 During the Cold War the international system was bipolar and, at its heart, so was its nuclear dimension. But this was not true in the new era. The bilateral character of the U.S.-Russian nuclear relationship was rapidly becoming trilateral as China’s changing nuclear profile impinged on Washington’s calculations and, at some level, presumably Moscow’s as well. And the nuclear standoff between India and Pakistan was growing more complex, as both India and China transformed their nuclear forces in ways that had direct implications for the other side.

Over the forty years of the Cold War, leaders, defense planners, and pundits slowly came to understand the dynamics of a two-sided nuclear competition in a two-sided global setting—even if that setting began to lose its cohesion in its later years. But how were the dynamics of a many-sided nuclear world, with pairings and triangles multiplying, in a fractured international political setting to be understood?

In a nuclear world no longer shaped exclusively by two nuclear superpowers but by the actions of, at a minimum, five nuclear-armed states (China, India, Pakistan, Russia, and the United States), this change introduced one further complication: among the five states, three—China, India, and the United States—viewed themselves in three-way contests and saw themselves increasingly compelled to design their forces for dual nuclear adversaries. The other two—Pakistan and Russia—remained focused on a single nuclear adversary, although for Russia it was a nuclear adversary with nuclear allies.

Finally, in the Cold War nuclear era, once France, Britain, and China acquired nuclear weapons, any one of them could have triggered a nuclear conflict. But the hierarchical character of the Cold War world order tightly subordinated that risk to the central contest between the United States and the Soviet Union. With the collapse of that order no such constraint existed. Among nuclear-weapons-possessing states a nuclear conflict could be ignited from multiple directions. Indeed, the likelihood of a nuclear weapon being fired in anger, until recently, seemed less likely in a core relationship, such as between Russia and the United States, than in the friction-laden relationship between India and Pakistan or from the unpredictable actions of a regime like that in North Korea. Here the loosening contours of the international political system had intersected with the shifting parameters of the nuclear world to make both less stable and less predictable.

In the end, however, whatever the underlying character or structure of the international system, its direct impact on developments within the world of nuclear powers and, in turn, their impact on it depend on the course of relations between and among these states. The United States and Russia have gone from a period of relative comity in the post–Cold War era to a period of hostility with key characteristics of a cold war, and the deterioration has the potential to alter profoundly their nuclear postures. After years of relative inattention to their nuclear forces and, on the U.S. side, little thought of countering a Russian threat, both countries are again investing in modernizing all elements of their nuclear forces. As their relationship turns confrontational, each is again adjusting its thinking and resources to meet the threat it sees from the other side.

If the uneasy balance in the U.S.-Chinese relationship were to shift decisively toward strategic rivalry—that is, if one or both were to define the other as a primary national security threat, orient their defenses in significant part against the other, and form alliances designed to counter the other—the impact on their military planning and the place assigned to nuclear weapons would be substantial. The 2018 U.S. Nuclear Posture Review moves in that direction.

On the periphery of relations among the main nuclear actors, a ninth nuclear entrant has brought new concerns to this landscape. The speed with which North Korea has moved through the end stage in developing nuclear weapons capable of striking U.S. allies and bases in Northeast Asia and, at some point, the United States itself has transformed a political-diplomatic standoff into a potential military crisis with the risk of escalation to nuclear war. Even if the worst is avoided, other than in the unlikely case that North Korea is completely disarmed, the challenge will be to manage one more nuclear dyad in an already complicated security environment that threatens to grow more so if others in the region follow the Democratic People’s Republic of Korea’s example.7

Thus, two decades into the new century, with the U.S.-Russian relationship sinking deeper into a cold war, with tensions continuing between India and Pakistan, with the adversarial tone rising in U.S.-Chinese relations, and with the Korean imbroglio intensifying, the relations among nuclear players are giving a darkening cast to the complexities and dangers that distinguish a new multipolar nuclear era from its earlier bipolar predecessor. The deterioration in key relationships tilts the synergy between the evolution of the larger setting and developments in the world of nuclear powers in a worrying direction.

Endnotes

• 1While distinguishing this from the original Cold War—and the distinctions are fundamental—I have explored the depth of the deterioration and its major consequences in Robert Legvold, Return to Cold War (Cambridge: Polity, 2016).
• 2United States Department of Defense, Nuclear Posture Review Report, April 2010, iv.
• 3Ibid, v.
• 4United States Department of Defense, Nuclear Posture Review, February 2018, 6–12.
• 5Ibid., 6.
• 6Multipolarity is the description favored by most, but Samuel P. Huntington employed the more nuanced notion of uni-multipolarity in his “The Lonely Superpower,” Foreign Affairs 78 (2) (March/April 1999): 35–49. Unipolarity has been much argued over by a number of scholars, but the most recent hedged discussion of the issue is Stephen G. Brooks and William C. Wohlforth, “The Rise and Fall of the Great Powers in the Twenty-first Century: China’s Rise and Fate of America’s Global Position,” International Security 40 (3) (Winter 2015/16): 7–53. Richard Haass has argued that the current international system is essentially “nonpolar.” See Richard N. Haass, “The Age of Nonpolarity: What Will Follow U.S. Dominance,” Foreign Affairs 87 (3) (May/June 2008): 44–56.
• 7Scott D. Sagan, “The Korean Missile Crisis: Why Deterrence Is Still the Best Option,” Foreign Affairs (November/December 2017): 72–82.

Fitful change in the larger geopolitical setting, including potentially dramatic shifts in relations among the great powers, is carving a deep imprint on trends within this new multipolar nuclear era. In the first years after the Cold War, both the asymmetries resulting from the fracturing of a bipolar order and the contrasting way the United States and Russia were situated in the emerging order drove the two countries apart in their approach to nuclear deterrence.

During the Clinton administration, the United States began moving away from a “one-size-fits-all” notion of deterrence toward “tailored” deterrence.8 The preoccupation with a nuclear Russia faded and it was replaced by a greater concern over regional environments where, it was feared, local nuclear actors might in a crisis move swiftly by a variety of conventional and nonconventional means to create a fait accompli, and then checkmate a U.S. response with either a threatened or actual limited use of nuclear weapons.

By extension, maintaining the United States’ extended deterrence commitments emerged as the central concern in the Obama administration’s 2010 Nuclear Posture Review. It focused plans for missile defense and conventional strategic strike forces, justified blending conventional warfighting, cyber, and political elements into a new and more comprehensive conception of deterrence, and framed the role of nuclear weapons within it. The threat varied from Europe to the Middle East to Northeast Asia, but in all cases, while the specific combinations contributing to deterrence differed, they all included reliance on sub-strategic nuclear weapons in or near the region backed by the full force of a modernized U.S. strategic nuclear triad.

Russia, in contrast, continued to see nuclear deterrence in a more monochromatic fashion, but with a larger role for nuclear weapons. While the United States, as it shifted its focus to deterring a regional adversary armed with nuclear weapons, urged moving away from the Cold War notion of mutual assured destruction (MAD) to what some referred as “mutual assured stability,” Russia remained wedded to the older notion.9 The purpose of its nuclear forces, as Alexei Arbatov and Vladimir Dvorkin noted, remained threefold: to retaliate when Russia “or its allies” were subject to an adversary’s nuclear first strike; to retaliate against an aggressor’s attack with chemical or biological weapons; and to counter an “imminent national catastrophe resulting from a conventional attack on Russia.”10 But the core task was war—not, as in the U.S. case, nuclear blackmail, nuclear brinksmanship, and the maneuvering of a nuclear-armed regional predator.

While the Russian emphasis too was on regional war and not a general or large-scale nuclear war, which Russian officials treated as unlikely, a sharp contrast existed between the U.S. and Russian approaches to conventional warfighting and nuclear deterrence. In the U.S. case, conventional options—standoff conventional strike forces, prompt global strike, weaponry in space, and improved intelligence, surveillance, and reconnaissance (ISR)—were viewed as adapting and enhancing nuclear deterrence. In the Russian case, adjusting nuclear deterrence—incorporating the use of sub-strategic nuclear weapons, developing weapons for “pre-nuclear deterrence,” and toying with the concept of escalating to nuclear use to de-escalate a conventional conflict—was intended to enhance its capacity to wage a conventional war.11

That was then. The contrast has since narrowed. In the 2018 U.S. Nuclear Posture Review, while programmatic aspects remain largely unchanged, the assumptions underpinning them are dramatically different. Modernizing the U.S. triad is still a priority, but not as interim insurance pending progress toward global nuclear disarmament. Instead, it is key to U.S. nuclear deterrence, and U.S. nuclear deterrence is the cornerstone of U.S. national defense in a seriously deteriorating threat environment.

As before, the challenge of preserving extended nuclear deterrence is central, requiring a more thorough integration of nuclear and nonnuclear resources, but in this mix, the introduction of new nuclear weapons, such as sea-based cruise and low-yield ballistic missiles, is meant to enhance the nuclear component by reducing the constraints on nuclear use. The stress on flexibility, the role of conventional weapons in nuclear deterrence, and the importance of keeping technological options open is not treated, as earlier, as part of an evolution away from nuclear deterrence, but as recognition that nuclear deterrence provides a margin of safety that conventional deterrence cannot.

The 2018 Nuclear Posture Review, like its predecessor, emphasizes that “there is no ‘one size fits all’ for deterrence.” Therefore, “the United States will apply a tailored and flexible approach to effectively deter across a spectrum of adversaries, threats, and contexts.”12 But while the “spectrum” includes North Korea, Iran, and terrorist organizations, the tailoring is now focused on major adversaries bent on far-reaching geopolitical change and armed with substantially enhanced nuclear capabilities.

Meanwhile other changes also have shrunk the earlier gap between U.S. and Russian approaches to nuclear deterrence. Like the previous U.S. position, Russia now emphasizes the importance of relying less on nuclear deterrence by strengthening nonnuclear deterrence. In early 2017 Russian Defense Minister Sergei Shoigu, as if taking a page from the Obama administration, boasted that, because of Russia’s rapid development of precision-guided conventional weapons, the country’s nonnuclear forces would increasingly substitute for nuclear weapons, eventually fully providing for the country’s national security.13

In this respect, the post-1999 much discussed Russian concept of using nuclear weapons to de-escalate a conventional military conflict, had it ever been official strategy, was receding at the same time the United States was giving greater attention to developing sub-strategic nuclear weapons to counter it. An artifact of the period when Russian conventional forces were weak, and apparently never incorporated into operational war plans, it faded as Russian defense planners began to stress a broader notion of strategic deterrence, one combining nuclear deterrence with conventional forces and even nonmilitary assets, such as information warfare and economic leverage.14 Yet this did not mean Russia had stopped thinking about the limited use of nuclear weapons, however that might be defined. On the contrary, like the United States, in the weapons it now featured, Russia concentrated on those whose characteristics increased both their usability and their interoperability with conventional alternatives.

Russia, like the United States, embraced the need for “tailored” deterrence, and its notion of it included a role for precision-guided, dual-capable cruise missiles and sub-strategic weapons. Here, however, its inspiration put the two countries at cross purposes that increased the possibilities for miscalculation. In the U.S. case, tailored deterrence is meant to rescue its beleaguered extended deterrence commitments against multiple adversaries in different, but increasingly complex, environments. Russia is preoccupied with strengthening its national strategic deterrent against a single adversary in one critical strategic arena—Europe. The trigger for the United States is an adversary intent on using its nuclear leverage to blackmail a weaker neighbor or neighbors, or on seizing territory and then using nuclear threats to paralyze a response. The trigger for Russia is U.S. plans to tailor the development and use of nuclear weapons to allow it to exploit its conventional arms advantage in a European crisis. Symmetry in the case of “tailored deterrence” has the potentially perverse effect of reducing the barrier to early nuclear use by one or both sides.

In other respects, however, Russia and the United States are distinctive in the positions they share beyond their long-standing uneasy reconciliation with mutual assured destruction. They refuse to accept mutual deterrence as the basis for their relationships with other nuclear powers—most notably China.15 In part this is the inertia of attitudes formed during an earlier era, but, more tellingly, the fact is neither country is eager to acknowledge that its nuclear relationship with China rests on “mutual vulnerability.” Second, both reject pledging that they will not be the first to use nuclear weapons. As stated in the 2018 Nuclear Policy Review, “the United States has never adopted a ‘no first use’ policy and, given the contemporary threat environment, such a policy is not justified today. It remains the policy of the United States to retain some ambiguity regarding the precise circumstances that might lead to a U.S. nuclear response.”16 Russia’s position is equally explicit. Beginning with its 2000 military doctrine, it reserves “the right to use nuclear weapons . . . in response to large-scale aggression utilizing conventional weapons in situations critical to the national security of the Russian Federation.”17

Both countries also reject the principle that the “sole purpose” of their nuclear weapons should be to deter a nuclear attack. The United States in its formally articulated nuclear posture insists on retaining the right to respond to a nonnuclear attack on itself or its allies with nuclear weapons, and has in its most recent iteration broadened the categories (e.g., to include critical infrastructure) and forms of attack (e.g., potentially cyber) that could be subject to nuclear retaliation. Russian military doctrine, as noted, expressly sanctions the use of nuclear weapons in retaliation for a chemical or biological attack on itself or its allies (as does its U.S. counterpart), as well as a fundamental “threat to the state’s existence” in a conventional war.18 Again, as in other respects, the hardening of tensions between Russia and the United States, together with the threats a fracturing nuclear world poses, exert a negative effect—in this case by raising the already considerable barriers to transforming the principle of no first use and sole purpose into universal nuclear norms.

China now adds a third dimension to the central U.S.-Russian nuclear relationship, at the same time that it complicates the Indian-Pakistani nuclear relationship. Like Russia and the United States, China bases its approach to nuclear deterrence on “assured retaliation.” Unlike Russia and the United States, however, but like India, it has committed itself to a doctrine of minimum deterrence and no first use of nuclear weapons. As a result, the asymmetries at both the international political and the nuclear level generate tension.

Over the last decade the rise of China as a great power has also featured the development of nuclear forces with a genuine, albeit rudimentary, capability of assured retaliation. In this context, it matters to the Chinese that the United States appears unwilling to accept a relationship of mutual vulnerability. Even more, as a number on the Chinese side argue, the United States is bent on a force modernization effort intended to give it “nuclear primacy”—that is, a combined offensive-defensive advantage allowing it to strike with nuclear weapons without fear of significant nuclear retaliation.19

China’s initial and likely further steps to preserve an assured retaliatory capability against the United States—by enlarging and modernizing its intercontinental ballistic missile (ICBM) force, developing a sea-based deterrent, and exploring missile defense—in turn stir Indian concerns. How real is the Chinese commitment to minimum deterrence, wonder Indian observers, when the country is increasing the number and accuracy of its ICBMs, adding multiple independently targetable reentry vehicle (MIRVed) missiles, and testing hypersonic weapons technologies?20 What stock is to be put in the Chinese pledge of no first use, if in order to minimize the vulnerability of China’s assured retaliatory capability, some Chinese are debating the virtues of a launch-on-warning option?

Generally, the parallel commitment of China and India to minimum deterrence and a no-first-use posture has been seen as stabilizing. At one level it is, but it still leaves China’s Second Artillery Force (now the People’s Liberation Army [PLA] Rocket Force) targeting ���Ի徱��’s cities and key strategic sites, and, since at least 2009, the Indian Army “preparing for a two-theater war with Pakistan and China under nuclear conditions.”21 Here too, however, the rapidly growing nuclear capacities of India and China, as each pursues advanced offensive and defensive capabilities serving what will be the world’s third and fourth nuclear triads, in the context of each country’s growing international ambitions, casts a different light on their core postures, particularly when the mistrust and military tension in the bilateral relationship remain.

Among the conflicting approaches to nuclear deterrence separating nine nuclear actors, the most unsettling are those in the Indian-Pakistani relationship. Each speaks of “credible” minimum deterrence, offered as justification for pressing to create a secure second-strike capability (although Pakistan’s altered notion of “full-spectrum” deterrence—that is, the threat to use battlefield nuclear weapons against a conventional attack—rather warps the concept). And each has set about building an air, land, and sea triad. Theoretically, both developments should be stabilizing. A secure second-strike capability will eliminate the highly unstable character of first-generation nuclear forces that depended on a limited number of aircraft to deliver a nuclear strike, and a triad helps to mitigate Pakistan’s strategic depth problem. But one similarity and two dissimilarities cloud this reality. The similarity resides in the four to six minutes it would take for a nuclear weapon to reach the capitals and major population centers in both countries, overwhelming even the most sophisticated early-warning system.

The dissimilarities are more portentous. In India nuclear decision-making occurs under a single national civilian command: the Political Council of the Nuclear Command Authority, chaired by the prime minister. It is not clear if this is also the case in Pakistan. Technically, decision authority there is invested in the Employment Control Committee of the National Command Authority, a multi-member group that supposedly can act only on the basis of consensus, but the suspicion lingers that the military’s finger is near the nuclear trigger.

The imbalance in the military balance, however, carries the most significant implications. Because of ���Ի徱��’s assumed conventional military superiority, Pakistan from the outset has reserved the right to respond to a conventional attack with nuclear weapons, and it refuses to reciprocate ���Ի徱��’s no-first-use position. Since 2004, when the Indian Army announced a so-called “Cold Start” conventional strategy—that is, the formation of smaller, rapid-reaction, forward-deployed battle units (although with limited follow-up)—Pakistan has threatened to respond to advancing conventional forces with battlefield tactical nuclear weapons, and has begun rapidly developing a short-range tactical ballistic missile, the Nasr, to deliver them.22 Indian officials have stressed that India will answer any use of nuclear weapons with “punitive” nuclear retaliation.23 Assuming that Pakistan would then respond in kind, the prospect of a largescale, countervalue nuclear war becomes real.24

The perils in ���Ի徱��’s and Pakistan’s evolving nuclear postures may be the most immediately and palpably disturbing, but the risks and complexities now reverberating through many dimensions of this multipolar world and among its other actors also are mounting. The intersecting contrasts in a mutating international setting and a fragmenting universe of nuclear weapons states come together most consequentially in three related contexts: the prospects for crisis stability, plans if deterrence fails, and notions of victory in war.

Endnotes

• 8Brad Roberts, The Case for U.S. Nuclear Weapons in the 21st Century (Stanford: Stanford University Press, 2015), 18.
• 9International Security Advisory Board, Report on Mutual Assured Stability: Essential Components and Near Term Actions, U.S. Department of State, August 14, 2012, . See also Celeste A. Wallander, “Mutual Assured Stability: Establishing US-Russia Security Relations for a New Century,” Atlantic Council Strategic Analysis, July 29, 2013.
• 10Alexei Arbatov and Vladimir Dvorkin, The Great Strategic Triangle, Carnegie Papers (Washington, D.C.: Carnegie Endowment for International Peace, April 2013), 16.
• 11Andrei Kokoshin, Ensuring Strategic Stability in the Past and Present: Theoretical and Applied Questions (Cambridge, Mass.: Belfer Center for Science and International Affairs, Harvard Kennedy School, June 2011), 57–58.
• 12Nuclear Posture Review, 2018, vii–viii.
• 13Zaki Shaikh, “Russians Working on Non-nuclear Deterrence,” Anadolu Agency, January 30, 2017, .
• 14Kristin Ven Bruusgaard, “The Myth of Russia’s Lowered Nuclear Threshold,” War on the Rocks, September 22, 2017, .
• 15Arbatov and Dvorkin, The Great Strategic Triangle, 13.
• 16Nuclear Posture Review, 2018, 22. During the Obama administration the rationale for adjuring a no-first-use posture was that it was necessary to assure allies, and, hence, dull their desire to develop nuclear weapons of their own.
• 17“Russia’s Military Doctrine,” Arms Control Today, May 1, 2000, trans. U.S. Foreign Broadcast Information Service from Nezavisimaya Gazeta, April 22, 2000, .
• 18The reformulation in the 2010 and 2014 Russian military doctrine. An English translation of the 2010 doctrine is available at . An English translation of the 2014 doctrine is available at: .
• 19Fiona S. Cunningham and M. Taylor Fravel, “Assuring Assured Retaliation: China’s Nuclear Posture and U.S.-China Strategic Stability,” International Security 40 (2) (Fall 2015): 7–50.
• 20Srikanth Kondapalli, “Revisiting No First Use and Minimum Deterrence: The View from India,” in The China-India Nuclear Crossroads, ed. and trans. Lora Saalman (Washington, D.C.: Carnegie Endowment for International Peace, 2012), 58.
• 21Ibid., 63. Kondapalli is citing a statement by the Indian Army Chief General Deepak Kapoor.
• 22Jaganath Sankaran, “Pakistan’s Battlefield Nuclear Policy: A Risky Solution to an Exaggerated Threat,” International Security 39 (3) (Winter 2014/15): 118–151.
• 23Indian spokesmen and ���Ի徱��’s formal doctrine abjure the use of the phrase “massive retaliation.” How close “punitive” is to “massive” remains unclear.
• 24Privately some senior Indian defense officials suggest that actual operational plans contain a range of options, from “nuclear demonstrations shots” to “tactical use against military area targets on the conventional battlefield” to “use against other counterforce targets.” If so the discrepancy with the formal public posture scarcely contributes to stability. Ashley J. Tellis, quoted in Gaurav Kampani, “���Ի徱��’s Evolving Civil-Military Institutions in an Operational Nuclear Context,” Carnegie Endowment for International Peace, June 30, 2016.

In its simplest meaning, crisis stability in a world of nuclear powers exists when in a political-military crisis the incentive to use a nuclear weapon is low or nonexistent. This is normally thought of as assured when nuclear adversaries have a secure (nuclear) second-strike capability. The lesser version with lower requirements imagines that each nuclear-armed state in a crisis would have options, nuclear or otherwise, discouraging the other side from using nuclear weapons first. Crisis stability conceived in these terms may make sense in a dyadic relationship, but does it make sense in more complex configurations? What would it require? How would it be executed?

In the present international context, for all the change underway, the risk of a nuclear confrontation between more than two countries may seem merely hypothetical, but the fact that Indian military leaders think in terms of a twofront war against Pakistan and China “under nuclear conditions” makes the hypothetical seem less remote. And were today’s amorphous, but deteriorating, international setting to give way to unambiguous strategic rivalry among major powers—foremost the United States and China in parallel with an adversarial U.S.-Russian relationship—the hypothetical would weaken further.

The challenges to crisis stability, however, are already written into the intricate nexuses marking a multipolar nuclear world. Even in the most settled nuclear relationship—that between the United States and Russia—they are resurfacing. When the United States shifted the focus of its nuclear posture from the standoff with the Soviet Union to shoring up deterrence in critical regional contexts, it embraced a more comprehensive approach in which nuclear weapons were only one element. To deal with the stages of an escalating regional crisis, whether with North Korea, a future nuclear-armed Iran, China, or Russia, it placed increasing emphasis on rapid-reaction conventional forces, conventional-strike forces, limited ballistic missile defense, cyber and space defense, and an enhanced division of labor with defense partners.25 In this mix, the nuclear component was “tailored” to the region, but in most instances it included present or readily available sub-strategic nuclear weapons.

From a U.S. perspective, this evolution was meant to diminish the importance of nuclear weapons and strengthen strategic stability with Russia and China, while giving the United States and its allies flexibility and an appropriate counter to any move an adversary might contemplate—from political blackmail by nuclear intimidation to a swiftly executed fait accompli, to an escape from a conventional conflict gone bad by limited nuclear escalation.

Seen from Moscow, all of this was judged quite differently. Technically qualified Russians might have understood that elements of this program, such as limited missile defense and conventional prompt global strategic strike weapons, did not in their present form threaten Russia’s nuclear deterrent, but Russia’s leadership appeared to view these steps as of a package aimed eventually at neutralizing Russia’s nuclear defenses and giving free range to the use of U.S. conventional forces.26

Framing the issue in these terms did not imply that crisis stability was yet menaced—only that, from a Russian perspective, if the United States continued down this road, it might be in the future. What it did now, however, was threaten arms race stability. If Russian leaders were serious about the potential threat they saw in U.S. efforts—or, alternatively, security and military-industrial interests were simply seizing an opportunity—the Russian response seemed sure to stimulate U.S. countermeasures. And so it has.

The Russian side has justified the development of the heavy, MIRVed, liquid-fueled, silo-based “Sarmat” ICBM replacement for the SS-18 “Satan” missile as ultimate insurance guaranteeing its ability to penetrate any ballistic missile defense that the United States might build. But in the context of Russian efforts to modernize its entire ICBM force, introduce a new fourth-generation nuclear-powered ballistic missile submarine (SSBN) armed with new, independently maneuverable nuclear missiles, a modernized Tu-160 bomber, and in the future perhaps a PAK-DA stealth bomber with advanced air-launched cruise missiles (ALCMs), the U.S. defense community now treats it as an ambitious program to put at risk key elements of the United States’ nuclear deterrent. Presumably so will the U.S. side also interpret the new Russian long-range, standoff, air-launched high-precision cruise missiles, particularly the Kh-102, its nuclear variant, as a bid to achieve escalation dominance in the initial phases of a conventional conflict.

Earlier the United States might have responded to much of this with greater equanimity, treating a good many of these systems as part of a normal replacement process. Now, however, as the two countries sink back into cold war, the effort is assessed quite differently, underscoring how central the political factor is in shaping key nuclear trends.

Moreover, in the penumbra of a U.S.-Russian relationship turned adversarial, there is another pathway to crisis instability. Most likely it does not pass through the vague but hypertrophied notion that agitates much of contemporary Western analysis—that is, that Russia believes that in a conventional war with NATO the violence can be “de-escalated” by the limited use of nuclear weapons.27 That idea, as noted earlier, had play after the 1999 Kosovo War, when Russian military analysts were struggling to address Russia’s conventional force inferiority, but the evidence that it was ever what Western observers understood it to be, let alone a concept integrated into operational war planning, remains murky.28

Less noticed, however, is a new factor uniting the menacing turn in U.S.-Russian relations with a major strategic military development whose nuclear dimension heightens the risk of inadvertent nuclear war. For some time

U.S. defense planners have worried that China is building a capability that would allow the PLA to deny U.S. military forces access to the South China Sea and the Sea of Japan, and eventually to the area within the “second island chain” bordering the Philippine Sea. These are operating areas critical to U.S. security guarantees to South Korea and Japan. The strategy is called anti-access/area denial (A2/AD), and it incorporates modernized cruise and ballistic missiles, including potentially hypersonic glide vehicles and aircraft, as well as the intelligence, surveillance, target acquisition, and reconnaissance facilities (ISTAR) needed to operate them. More recently the United States and its NATO allies have begun to focus on a comparable Russian threat in Europe. New Russian land and sea-based precision-guided cruise missiles, forward-deployed sub-strategic ballistic missiles, and the planned ballistic missile defense system A-235, they fear, create an A2/AD problem compromising their ability to defend the eastern portion of the alliance from the Baltic Sea to the Black Sea.

Over the same period, on the other side, Russian defense planners have placed the accent on “air-space attack” as a principal threat to their country. As one Russian source puts it, “air-space itself will become the main and, at times, the only sphere of armed conflict. In these circumstances the enemy will get the opportunity to inflict coordinated, in time and space, high-precision strikes against virtually all targets on Russian territory, and indeed across the  entire world.”29 The war the Russians anticipate centers on the United States’ precision-guided cruise and ballistic missiles, aircraft, and space resources, and begins with a heavy conventional assault, but at some point goes nuclear.

A strategy designed to impede or prevent an adversary’s control over the strategic approaches to the homeland is not a new phenomenon. The Soviet Union through the last half of the Cold War strove to erect a three-thousand-kilometer land and sea defense perimeter around itself.30 But the contemporary A2/AD issue represents something new, not merely because it involves two different potential adversaries in two different strategic arenas—one maritime, the other on land—but, in the Russian case, because of the way it intersects with Russia’s preoccupation with air-space war.

In both cases, each expects a war to begin at the conventional level: the United States as the result of Russian aggression, whether open or surreptitious, against an adjacent NATO ally or allies. Russia’s A2/AD potential makes what is suddenly a more complex U.S. extended deterrence commitment still more complicated, and provides further justification for weapons systems such as the proposed Long Range Standoff air-launched cruise missile (LRSO) and the new nuclear precision-guided gravity bomb B61-12. The Russians, for their part, speak of a large-scale air and space attack similar to, only massively more elaborate than, the air war waged against Serbia in the 1999 Kosovo crisis.

To defeat the threat that each now ascribes to the other, each counts heavily on dual-use cruise and ballistic missiles and aircraft. While each assumes its own use of these weapons, at least at the outset of the conflict, would be in a conventional mode, nothing guarantees that the other side will be sure the attack is not nuclear and will not react accordingly. Moreover, when nuclear armed, these weapons are more accurate with lower yields and are designed for limited use. For example, presumably as part of a Russian A2/AD strategy, the Iskander-M nuclear-capable sub-strategic missile slated for permanent deployment in the Kaliningrad region would be targeted on the U.S. ballistic missile defense site planned for Poland. The U.S. nuclear-armed LRSO is defended sometimes as needed in order to blast a hole in an opponent’s air defenses, permitting U.S. strategic aircraft to complete their missions.31 In addition, on the U.S. side, there is a case for weapons that allow the United States to wage limited nuclear war to increase a president’s decision-making flexibility and enhance nuclear deterrence. On the Russian side, the case is made that the limited use of nuclear weapons may be necessary, if Russia’s defenses are overwhelmed in a large-scale air-space attack.32

Further complicating the issue, as technology advances and the United States and Russia alike develop advanced conventional strategic strike weapons, including precision-guided hypersonic cruise missiles and hypersonic boostglide vehicles, each places greater emphasis on nonnuclear deterrence. In this case, nonnuclear deterrence heightens the risk of “entanglement”—that is, once the firing begins attacks intended to destroy conventional weapons and their support systems may unintentionally hit colocated or dual-capable nuclear weapons and their command-and-control networks, including early-warning satellites, triggering an escalation to nuclear war.

The danger grows because advances in conventional cruise and ballistic missiles and potentially hypersonic boost-glide vehicles make their use against softer nuclear weapons targets and their associated facilities—as well as for a “decapitation strike” against national leadership—plausible. This blurring of the line between conventional and nuclear war adds to the risk that, in a crisis, if one or both sides act on the fears and calculations generated by the matrix of new threat analysis, weapons advances, and shifting attitudes toward nuclear use, the result could be, as Barry Posen long ago warned, inadvertent escalation to major nuclear war.33

If the shadow of crisis instability again darkens the U.S.-Russian nuclear relationship, it is potentially an equally acute matter in U.S.-China relations. The two realms—geopolitical and nuclear—intersect in this case in a less crystallized but more portentous way. At the geopolitical level, U.S.-Chinese relations do not suffer the sharp hostility now marking U.S.-Russian relations, but the implications, were this relationship to veer toward unambiguous strategic rivalry, are immense, and the uncertainty over whether that could happen grows steadily. Uncertainty at this level suffuses a rapidly evolving nuclear relationship with meanings that were absent when China remained in the shadows and its nuclear forces an afterthought. It bears on crisis stability both in a grand, if distant, sense and in a more concrete and immediate sense.

On the first score, China’s basic nuclear position—its commitment to minimum deterrence and its so-called “lean and effective” posture, coupled with a determination to possess an assured retaliatory capability—is suspended somewhere between the non-credible and the destabilizing. To boost a secure second-strike capability China’s ICBM program has advanced considerably, but remains vulnerable. Being able to reach parts or all of the United States with as many as seventy missiles, ten of which are MIRVed, has stirred the United States’ attention. And China’s ambitious program to begin deploying the road-mobile DF-41 ICBM, expected to carry up to ten MIRVed warheads, a MIRVed version of the DF-31A ICBM, and a new JL-2 submarine-launched ballistic missile (SLBM) for the second-generation Jin-class SSBN, promises to increase substantially the destructive power and flexibility of its nuclear forces. If the Chinese leadership were confident that all sixty ICBMs would reach their U.S. targets or, if in doubt, that the new weapons systems soon coming online will be able to do so, a secure second-strike capability would be in place, and between the two countries strategic stability qua MAD would have arrived. But neither condition—now nor near term—is a sure thing. Unless China, as some have speculated, may have hundreds of uncounted missiles secreted away in the sprawling tunnel system it has constructed, its relatively small number of fixed, liquid-fueled ICBMs, thirty-two road-mobile DF-31A ICBMs, and few limited-range SSBNs would not likely survive a concentrated nuclear attack by the United States.34

Moreover acquiring a genuine assured retaliatory capability for China may be an ever-receding prospect. Worse, its efforts to achieve qualitative, if not quantitative, strategic parity with the United States, combined with U.S. weapons advances blocking its path, risk still greater instability in a future crisis. Chinese leaders, as noted earlier, apparently believe the United States is straining to achieve “absolute security” through “nuclear primacy.” At the same time, while they evidently worry that U.S. efforts, including a persistent attempt to create a thick, integrated, multilayered missile defense system, advances in its ISR capabilities, and the further perfection of conventional strategic strike forces, could at some point imperil China’s nuclear deterrent, they remain ostensibly confident that for now the difficulty of locating all of their nuclear missiles and the ambiguity produced by the nontransparency of their nuclear forces and strategic thinking remain adequate to deter the United States.

It may be something of a gamble, particularly since the rapid advances China is making in all aspects of its nuclear arsenal are being matched by the qualitative transformation of the U.S. strategic deterrent. Over the last ten years, the United States has continued to develop capabilities, particularly in the accuracy of weapons and remote sensing, that may put at risk the ways China would ensure, and Russia has ensured, the resilience of its nuclear retaliatory forces. In its extreme form, Daryl Press and Keir Lieber call it the “counterforce revolution.”35 They argue that the enhanced accuracy of U.S. delivery systems and improved U.S. ability to locate and track opposing nuclear forces, coupled with the reduced size of the Russian force and the small size of the Chinese force, give the United States the theoretical possibility of executing a disarming first strike.

Whether this is so or not (Press and Lieber admit that against Russia in a real-world situation—i.e., in a crisis with Russian forces on alert—it is not) does not end the issue.36 What China (and Russia) make of these developments, quite apart from U.S. intentions or actual capabilities, is what matters: that is, what they make of the modified Trident II SLBM whose circular error probable (CEP) has reportedly been reduced four-fold with a new fuze system on the W76-1 warhead/Mk4A reentry vehicle; or the U.S. Air Force’s interest in kinetic orbital strike capabilities against targets in space and land; or the growing talk of a space-based ballistic missile defense system;37 or the prospect that the United States’ stress on nonnuclear deterrence means it now seriously intends to develop conventional counterforce weapons; or the U.S. plans to replace the platforms in all three parts of the triad rather than live within the Life Extension Program for some existing systems.

For China, in particular, the overall U.S. effort gives special resonance to what its leaders imagine may be the threat posed by U.S. ballistic missile defense and its emphasis on conventional precision-guided long-range strike capabilities. China almost certainly will take measures to counter any degradation of its efforts to develop an increasingly formidable assured retaliatory capability. Because China, as Russia, has the capacity to duplicate virtually any of the new technological directions taken by the United States, albeit with a lag, arms race instability looms in the future.

Yes, the Chinese insist they will not allow themselves to be drawn into a nuclear arms race, and that they intend to continue steering the course they are on. But it remains to be seen, if the core U.S.-China relationship veers toward increasing military hostility, whether this will hold. If not, in all likelihood an arms race between China and the United States, focusing particularly on the nuclear dimension, will unfold asynchronously, creating interludes of feared vulnerability on one side or the other. And in a competition that expands into new realms—space, offense-defense, lowered nuclear thresholds—the uneven incidence of the vulnerability feared will heighten the risk of crisis instability. Moreover, the moves and countermoves of the United States and China will, whatever currently is the level of Russian equanimity, eventually force Russian defense planners to focus on a two-sided challenge—and the triangular effects of the new nuclear era will then be real.

In the meantime, the source of crisis instability in a confrontation between the United States and China already exists. In its narrowest form it arises because China has begun deploying its main medium-range ballistic missiles (the DF-21C and DF-21D) in a conventional mode. As Hans Kristensen and Robert Norris note, “This potentially dangerous mix of nuclear and conventional missiles increases the risk of misunderstanding, miscalculation, and mistaken nuclear escalation in a crisis.”38 As mentioned earlier, entanglement is a new pathway to U.S.-Russia nuclear war, and it exists as well in the U.S.-China relationship.39

In a conventional war over Taiwan or the South China Sea region, given U.S. concerns with the A2/AD threat that China poses, any U.S. plans to attack—in all likelihood preemptively—Chinese aircraft bases, cruise missile sites (including mobile missile launchers), and the defense radars and command-and-control sites serving them could well be interpreted by the Chinese as the initial phase of a disarming nuclear first strike.40 Or, alternatively, China at the outset of a conventional war with the United States might try to blind

U.S. satellite communication facilities that are key to naval operations, which provides one explanation for China’s extensive efforts in anti-satellite (ASAT) technology.41 But these resources are also critical to the U.S. early-warning satellite system protecting against a nuclear attack.

In the midst of an evolving multipolar nuclear world, crisis instability nowhere looms more menacingly than in the Indian-Pakistani nuclear relationship. As already noted, in its rawest form the instability stems from the tensions between the two countries and the realistic possibility of war, with growing nuclear arsenals on both sides and plans for their use—in particular, Pakistan’s apparent and reckless intentions to use battlefield nuclear weapons against superior Indian conventional forces.42

The specific scenarios for what may happen described by experts dramatize what crisis instability really looks like. Of four possible scenarios, the first postulates that India might withdraw its troops from Pakistan after suffering the destruction from a single salvo of battlefield tactical nuclear weapons, calculating that having “managed to cause the obliteration of a part of Pakistan, with civilian deaths in the thousands, while losing only a portion of a regiment or brigade,” it had exacted adequate punishment for a Pakistani-originated terrorist attack.43 The second scenario assumes that India would take the hit and press on, facing the Pakistanis with a choice of attempting to avoid conventional defeat by launching larger numbers of battlefield tactical nuclear missiles or by escalating to a strategic nuclear attack on Indian military garrisons.44 And up the ladder it goes. If India acts as it promises to, and answers the use of any nuclear weapon with large-scale nuclear retaliation, the first of these scenarios is impossible; for the other three, it is simply a question of the path and speed by which the conflict escalates to a full-scale nuclear war.

There are, however, other threats to crisis stability in the Indian-Pakistani relationship and by extension in the U.S.-Chinese relationship that are less obvious. Theory argues that nuclear triads enhance strategic stability by providing redundant capabilities, flexibility in use, and security against attack. But these advantages fall away when countries are in the early stages of developing a triad. When the legs of the triad develop unevenly, as is the case with China, India, and Pakistan, redundancy is weak, flexibility is limited, and the security of the deterrent’s primary arm is menaced. For all three countries their land-based ballistic missile systems (along with aircraft in the Indian and Pakistani cases) serve this core function, and, when limited in size and in fixed locations, they are vulnerable to first-strike destruction by an adversary with superior nuclear forces.45 The risk of crisis instability grows when some of these missiles are MIRVed, as China is doing and India hopes to do, creating a powerful incentive for an opponent to preemptively destroy high-value concentrated targets.

At this early stage, the rudimentary development of all three countries’ seabased deterrents constitutes a special weak link in the chain guarding against crisis instability. India and Pakistan are in the process of nuclearizing the Indian Ocean, and, as each puts nuclear weapons to sea, the systems involved carry considerable risks, particularly those of Pakistan. Pakistan’s plans appear to include loading nuclear-tipped cruise missiles aboard conventional submarines and tactical nuclear weapons on surface ships and patrol aircraft. Pakistani planners explicitly embrace the deterrent value of strategic ambiguity and dual-use platforms.46 Moreover, while Pakistani military officials speak of naval nuclear weapons as intended to constitute a secure second-strike capability, they appear far more suited for conventional contingencies: that is, the use of tactical nuclear weapons aboard surface ships and aircraft against an Indian maritime blockade, and the use of nuclear cruise missiles for nuclear coercion in the face of an Indian conventional offensive. Either use would be instantly escalatory.

���Ի徱��’s program, because of the limited range of the ballistic missiles on its first two SSBNs, remains for the moment confined to targeting Pakistan. Beyond the destabilizing ambiguities surrounding Indian talk of deploying short-range ballistic missiles on dual-use surface ships, as India moves nuclear forces into the Arabian Sea and Pakistan counters, the weakness of both countries’ command-and-control systems over nuclear-armed submarines when on alert adds another element of instability.47

Over the horizon India intends to have an SSBN force capable of striking China, and with the F-5 SLBM and the fourth of five planned SSBNs, it will have achieved such a force. At that point both China and India will have fully functioning nuclear triads with elements of each leg a threat to the other’s nuclear deterrent. While the primary object of ���Ի徱��’s future SSBN force is China, the primary object for China is the United States. As India awaits a longer-range SLBM and an SSBN capable of carrying it in order to target China, so, too, does China need a longer-range SLBM than the JL-2 in order to target the United States. In the meantime, in a crisis, China could only rely on its sea-based deterrent by sending some or all of its four Jin SSBNs beyond the perilous choke points leading out of the South China Sea into the Pacific, where sophisticated U.S. anti-submarine warfare (ASW) would await.

Endnotes

• 25This is discussed in Brad Roberts, “The New Regional Deterrence Strategy,” in Roberts, The Case for U.S. Nuclear Weapons in the 21st Century, chap. 3.
• 26Vladimir Dvorkin cites an article in Voenno-Promyshlennyi Kur’er (Military-Industrial Courier) in which experts offer “detailed calculations that demonstrate the impossibility of simultaneous high-precision cruise-missile strikes against even one of the Strategic Missile Force sites in the European part of Russia.” See Dvorkin, “Risky Contradictions: Putin’s Stance on Strategic Arms and Missile Defense,” Carnegie Moscow Center, February 10, 2016, .
• 27Nikolai N. Sokov, “Why Russia Calls a Limited Nuclear Strike ‘De-escalation,’” Bulletin of the Atomic Scientists, March 13, 2014, .
• 28Olga Oliker has argued that formal Russian military doctrine, most military exercises, and arms modernization did not suggest that “escalate to de-escalate” was, in fact, actual Russian strategy. Nor, she argues, are there clear signs that Russia has in reality lowered the nuclear threshold. Olga Oliker, Russia’s Nuclear Doctrine: What We Know, What We Don’t, and What That Means (Washington, D.C.: Center for Strategic and International Studies, May 2016), .
• 29Andrei Demin, et al., “Sereznoi ugroze adekvatnyi otvet. Osnovnoi sferoi vooruzhennoi borby stanet vozdushno-kosmicheskoe prostranstva” [An appropriate response to a serious threat. The main area of armed conflict will be the air-space theater], Vozdushno-kosmicheskaya oborona, August 13, 2012, quoted in Alexey Arbatov, Vladimir Dvorkin, and Petr Topychkanov, “Entanglement as a New Security Threat: A Russian Perspective,” in Entanglement: Russian and Chinese Perspectives on Non-nuclear Weapons and Nuclear Risks, ed. James Acton (Washington, D.C.: Carnegie Endowment for International Peace, 2017), 14. This is the most careful analysis of the Russian notion of air-space war available in English.
• 30Christopher Cowan, “A2/AD—Anti-Access/Area Denial,” RealClearDefense, September 12, 2016, .
• 31Former U.S. Secretary of Defense William Perry, when serving as undersecretary of defense, engineered the development of the prior ALCM program. He now argues strenuously against acquiring the LRSO because of the “significant risk” it poses of “miscalculation and unintended escalation” to nuclear war, since the other side would not know when it was fired whether it was conventionally or nuclear armed. William J. Perry and Andy Weber, “Mr. President, Kill the New Cruise Missile,” opinion, Washington Post, October 15, 2015.
• 32Arbatov, Dvorkin, and Topychkanov, “Entanglement as a New Security Threat,” 19.
• 33Barry R. Posen, Inadvertent Escalation: Conventional War and Nuclear Risks (Ithaca, NY: Cornell University Press, 1991).
• 34Arbatov and Dvorkin, The Great Strategic Triangle, 10.
• 35Keir A. Lieber and Daryl G. Press, “The New Era of Nuclear Weapons, Deterrence, and Conflict,” Strategic Studies Quarterly 7 (1) (Spring 2013): 3–12.
• 36Keir A. Lieber and Daryl G. Press, “The End of MAD? The Nuclear Dimension of U.S. Primacy,” International Security 30 (4) (Spring 2006): 8.
• 37Sydney J. Freedberg, “Space-Based Missile Defense Can Be Done: DoD R&D Chief Griffin,” Breaking Defense, August 8, 2018, .
• 38Hans M. Kristensen and Robert S. Norris, “Chinese Nuclear Forces, 2015,” Bulletin of the Atomic Scientists 71 (4) (2015): 79.
• 39For a Chinese perspective on this risk, see Tong Zhao and Li Bin, “The Underappreciated Risks of Entanglement: A Chinese Perspective,” in Acton, ed., Entanglement, 47–76.
• 40This was apparently envisaged in the United States’ original Air-Sea Battle Concept. Whether it still is in its unmemorable replacement, the Joint Concept for Access and Maneuver in the Global Commons (JAM-GC), is less clear. The JAM-GC reads, “Whereas the ASB concept was designed to counter emerging A2/AD challenges and hinged on a ‘disrupt, destroy, defeat’ approach to specific adversary A2/AD capabilities, JAM-GC is focused on defeating   an adversary’s plan and intent, rather than just concentrating on dismantling adversary A2/ AD capabilities.” . A copy of the ASB Concept is available at
• 41The U.S. early-warning satellite system and key communications and signals intelligence systems operate in Geosynchronous Earth Orbit and Highly Elliptical Orbit at an altitude of 36,000 km. As a result, there is an increasingly vigorous U.S. debate underway over whether China, notwithstanding its apparently ambitious efforts in this sphere, is close to having the capability of attacking satellites at this altitude on the scale and complexity that would be required to be effective. For a skeptical assessment see Jaganath Sankaran, “Limits of the Chinese Antisatellite Threat to the United States,” Strategic Studies Quarterly (Winter 2014): 19–48. For the other side, see Bill Geertz, “China’s Great Leap in Space Warfare Creates a Huge New Threat,” Asia Times, September 13, 2017.
• 42To be sure, Pakistan’s precise plans are not entirely clear and apparently in some flux. In peacetime the missile system remains de-mated and out of the field of operations, but surging them toward the battlefield during a crisis and the logic of pre-delegated authority contain their own hazards. See Mansoor Ahmed, “Pakistan’s Tactical Nuclear Weapons and Their Impact on Stability,” Carnegie Endowment for International Peace, June 30, 2016, .
• 43Sankaran, “Pakistan’s Battlefield Nuclear Policy,” 147. The Nasr is mounted on a multi-tube launch vehicle.
• 44Evan Braden Montgomery and Eric S. Edelman, “Rethinking Stability in South Asia: India, Pakistan, and the Competition for Escalation Dominance,” Journal of Strategic Studies 38 (1–2) (April 25, 2014): 17, quoted in Sankaran, “Pakistan’s Battlefield Nuclear Policy,” 147.
• 45For now Pakistan has 140–150 systems capable of delivering nuclear warheads (36 by aircraft at two air bases, 102 by land-based ballistic missiles, and 12 groundand air-launched cruise missiles); India has 130–140 delivery systems (48 aircraft, 60 land-based ballistic missiles, and 60 sea-based); and China has 254 delivery systems (186 land-based ballistic missiles, 48 SLBMs, and 20 aircraft, plus a number of cruise missiles, some of which are nuclear armed). These figures are from the separate 2018 reports by Hans M. Kristensen and Robert S. Norris on all three countries, prepared for the Bulletin of the Atomic Scientists. Hans M. Kristensen and Robert S. Norris, “Pakistani Nuclear Forces, 2018,” Bulletin of the Atomic Scientists 74 (5) (2018); Hans M. Kristensen and Robert S. Norris, “Indian Nuclear Forces, 2018,” Bulletin of the Atomic Scientists 74 (6) (2018); and Hans M. Kristensen and Robert S. Norris, “Chinese Nuclear Forces, 2018,” Bulletin of the Atomic Scientists 74 (4) (2018).
• 46This and much of the following analysis of ���Ի徱��’s and Pakistan’s sea-based programs draws on Iskander Rehman, Murky Waters: Naval Nuclear Dynamics in the Indian Ocean (Washington, D.C.: Carnegie Endowment for International Peace, 2015).
• 47Ibid., 14–15. See also Usman Ansari, “Pakistan Unveils VLF Submarine Communications Facility,” Defense News, November 16, 2016, .

It is a perverse irony of nuclear deterrence, as Kenneth Boulding long ago observed, that to work “there must be a positive probability of it failing.” (And, as he would add, “anything which has a positive probability will happen if we wait long enough.”48) Thus, whether they do it consciously and systematically or casually and without strategic forethought, any country that goes to the trouble of acquiring nuclear weapons must face the prospect that what they hope nuclear weapons will prevent nonetheless may happen, and they must then decide what next. How carefully they think of this beforehand and prepare for it gives the final shape (or shapelessness) to that country’s nuclear posture. In a world of nine nuclear powers, asymmetries and troubling discrepancies reenter and take on greater force, because the trend in this new nuclear era is to conflate nuclear warfare with conventional warfighting.

The challenge posed by the failure of nuclear deterrence arises at two points: 1) when the peace is broken and a conventional war ensues with a genuine risk that nuclear weapons could be used, and 2) when a nuclear weapon is used. How precisely any of the nine nuclear powers would react at either point is not known (indeed, perhaps not even to those who would have to make the decision), but the evidence that exists suggests a large discrepancy among them. The gap is enormous between a United States that is again thinking hard about options not only in the event, but in the sequence of choices likely to follow, and a North Korea whose thinking, while denied to the outside world, is doubtless rudimentary, if it has even begun.

Part of the problem stems from the way different states define the failure of deterrence. Pakistani officials, for example, regard—or, at one point, did regard—any one of four events as justifying a nuclear response: 1) ���Ի徱��’s conquest of a “large part of Pakistan’s territory”; 2) the destruction of “a large part of either its land or air forces”; 3) ���Ի徱��’s attempt to “strangle” Pakistan economically; or 4) ���Ի徱��’s attempts to “de-stabilize” Pakistan politically or to stir “large-scale internal subversion.”49 How nuclear weapons might be used to control political instability abetted by India would seem to be something of a puzzle.50 True, the United States and Russia, in refusing to embrace the principle of “sole purpose,” leave open the possibility of responding with nuclear weapons to other than a nuclear attack, such as a biological or chemical weapons assault. And in the 2018 Nuclear Posture Review the United States has broadened the list of threats warranting a nuclear response to include an attack on vital infrastructure by nonnuclear means.

Another source of the ambiguity of what would happen if deterrence fails derives from the failure of governments to think carefully about the consequences if it does fail. ���Ի徱��’s posture of presumably large-scale nuclear retaliation is a case in point. Earlier as a declaratory doctrine this may have made sense, but how little sense it makes when Pakistan plots the use of battlefield tactical nuclear weapons against an Indian army that has breached its defenses is stirring debate in India.51 Because formally this remains ���Ի徱��’s posture, divining whether and how nuclear planners might employ nuclear weapons less apocalyptically is left shrouded. Similarly, on the Pakistani side, while its nuclear use doctrine remains classified, and though its emphasis on battlefield nuclear weapons suggests a shift in nuclear posture toward a “graduated response” strategy, hence, toward warfighting, little suggests that Pakistani planners have given much thought to controlling escalation once nuclear weapons are used.52 Worse, if Sadia Tasleem is correct, Pakistani thinking on nuclear use is apocalyptic: assuming, on the one hand, that “deterrence is infallible” and will not fail, and, on the other, that if it does “all-out war” follows, and escalation control is meaningless.53

Even between veteran nuclear powers, such as the United States and Russia, however, the gulf between their likely actions should deterrence fail may not only be large, but dangerous. Consistent with long-standing practice, as the post–Cold War lapse in thinking about nuclear weapons fades, U.S. defense planners are struggling with the actual use of weapons in war. According to Brad Roberts, who was close to the process during the Obama administration, instincts push toward devising ways by which nuclear weapons and their complements (missile defense, precision conventional strike forces, cyber capabilities) can, in refined fashion, be applied to checkmate an opponent’s choices at each rung up the escalatory ladder.54

Because the United States is preoccupied with the threat posed by adversaries willing to gamble that they can create facts on the ground and then coerce U.S. and allied capitulation by threatening to use, or actually using, nuclear weapons (sub-strategic in the Russian case, crude in the North Korean case), U.S. planners focus on an opponent’s decision points, tailoring the limited and discriminating use of nuclear weapons to dissuade the opponent from making the next move. As Roberts and others have stated, it is a theory of limited nuclear war.55 It privileges what Roberts calls forward-deployed nonstrategic nuclear weapons—i.e., deployed within the region and delivered by nonstrategic systems—with the goal of demonstrating collective alliance resolve and delegitimizing a nuclear retaliatory attack on the U.S. homeland. It also assumes the United States has accurately understood the other side’s calculations and likely chess moves once the nuclear threshold has been crossed. Chances are, however, that is not so in the Russian case, and in all likelihood not in the Chinese case either.

True, an ambitious Russian Air-Space Defense program as a counter to U.S. and NATO subsonic cruise missiles and hypersonic systems can be interpreted as Russia planning for a limited nuclear war fought along the lines imagined by the United States. But some, including Alexei Arbatov, have made a strong case that it is not in the mentality of the Russian military to think in terms of influencing, rather than removing, an opponent’s choices in the fog of war, to embrace subtle concepts of intra-war deterrence, or to bind themselves by principles of discrimination and proportionality in the design and employment of nuclear weapons.56 On the contrary, while Russia may treat regional war as less unlikely than global war, this does not mean that Russian defense planners think like the Americans about a regional limited nuclear war.

With the exception of a brief interlude in the late 1990s, when, as Arbatov reports, a special commission of military and civilian experts on strategic force planning recommended steps to enhance strategic stability by de-emphasizing counterforce targeting, stressing “force survivability,” and favoring low-yield weapons, the Russian military has never seen warfighting as a chess match, and instead plans to use any and all means to avoid defeat.57 Accordingly it would be foolish to assume that, if deterrence fails, Russia would act as the United States assumes, and use sub-strategic nuclear weapons for nuclear “signaling” or “blackmail” and long-range standoff precision weapons to control escalation rather than as the best way to prosecute the war.58 In this case, the discrepancy between U.S. and Russian plans and mental outlook, should deterrence fail, contains a high risk of miscalculation leading to inadvertent escalation.

This may also be true in the U.S.-Chinese relationship, although its basis may be less in mismatched plans when each side approaches or crosses the nuclear threshold than in the ambiguities bringing them to this point. Chinese sources discuss a “theory for ‘war control,’” including “the scale, pace, scope, and intensity of conflict.”59 This, however, scarcely means that Chinese planners have worked out a notion for the graduated use of nuclear weapons, and, while they speak of a larger or smaller retaliatory strike to achieve unacceptable damage, their formal position remains no first use. Nor is there evidence that they plan for—or are capable of—a protracted nuclear contest with repeated nuclear exchanges. Indeed, Taylor Fravel and Fiona Cunningham contend that Chinese planners, while attentive to managing escalation in a conventional war, have largely ignored the issue once the nuclear threshold is crossed.60 This is because the Chinese believe that escalation cannot be controlled in a nuclear war and because they are confident the United States will not intervene in a war between a U.S. ally and China if it risks nuclear conflict.

Uncertainties and dangers also arise because of the ambiguities of who would do what at the outset of hostilities. Were the United States, in carrying out a conventional attack, to strike colocated Chinese nuclear cruise missiles mistaken for conventionally armed missiles, China’s no-first-use policy would be stressed. Once China faced a decision to use nuclear weapons, the risk of instant or rapid escalation to large-scale nuclear war would be very high. Or, alternatively were China to destroy U.S. satellites essential to its naval operations, but also as early warning of a nuclear attack, confident the United States would trust China’s no-first use doctrine and disinclination to commit nuclear suicide, the consequences of a faulty calculation would be severe.61

If the potential perils inherent in the contrasting and, probably misperceived, likely reactions of the United States, Russia, and China in the actual event of nuclear war ought to be worrying, they pale in comparison to those surrounding the uncertainties between and among Pakistan, India, and China. The risk of miscalculation looms large, because planning a realistic response to a near or actual nuclear attack remains an obscure and almost certainly ill-thought through matter in two and perhaps all three of these countries. ���Ի徱��’s apparent “belief that nuclear weapons are only for retaliation and have nothing to do with Indian war planning,” reinforced by an organizational void that leaves India without a decision-maker to “control the escalation ladder or manage the conventional-nuclear interface,” underscores the point.62 Because India and Pakistan both are focused on prevailing in a limited conventional war (India, on keeping war below Pakistan’s nuclear threshold; Pakistan, on using battlefield tactical nuclear weapons without provoking nuclear retaliation), serious thinking about options once nuclear weapons are fired goes by the boards.63 How then does one begin to imagine choices for India, if it becomes a two-front war? And how would Pakistan and China play their respective hands in this instance? The ambiguities of this new multipolar nuclear era and the dangers they pose do not end here. Near the end of the Cold War, leaders on both sides recognized, as Ronald Reagan emphasized in 1984, that “a nuclear war cannot be won, and must never be fought.” By extension neither should a conventional war be fought between nuclear weapons states because it carries the risk of ending in nuclear catastrophe. In this new age the fear of an all-out nuclear war remains, but it is being eclipsed by approaches to national security that once more embed a role for nuclear weapons in a conventional armed conflict—only in ways that leave the players on perilously different wavelengths, each preparing for radically different contingencies.

Endnotes

• 48Kenneth E. Boulding, “Moving from Unstable to Stable Peace,” in Breakthrough: Emerging New Thinking: Soviet and American Scholars Issue a Challenge to Build a World beyond War, ed. Martin Hellman and Anatoly Gromyko (New York: Walker, 1988), 162.
• 49Rehman, Murky Waters, 16–17. He is citing a 2002 statement by Lieutenant General Khalid Kidwai, then director of Pakistan’s Strategic Plans Division.
• 50It seems unlikely that the portfolio of threats justifying Pakistan’s nuclear retaliation remains this broad, but there is still considerable ambiguity over just how broad it is. See Zachary Keck, “Pakistan Says It’s Ready to Use Nuclear Weapons—Should India Worry?” National Interest, November 3, 2017, .
• 51Shashank Joshi, “An Evolving Indian Nuclear Doctrine?” in Deterrence Instability and Nuclear Weapons in South Asia, ed. Michael Krepon, Joshua T. White, Julia Thompson, and Shane Mason (Washington, D.C.: Stimson Center, April 2015), 69–94.
• 52Sadia Tasleem, “Pakistan’s Nuclear Use Doctrine,” Carnegie Endowment for International Peace, June 30, 2016, .
• 53Ibid., 7.
• 54Roberts, The Case for U.S. Nuclear Weapons, especially chap. 3 and chap. 6, “Extended Deterrence and Strategic Stability in Europe.”
• 55Ibid. See also Jeffrey A. Larsen and Kerry M. Kartchner, eds., On Limited Nuclear War in the 21st Century (Stanford: Stanford University Press, 2014).
• 56Alexei Arbatov, “Challenges of the New Nuclear Era: A Russian Perspective,” in Linton Brooks, Francis J. Gavin, and Alexei Arbatov, Meeting the Challenges of the New Nuclear Age: U.S. and Russian Nuclear Concepts, Past and Present (Cambridge, Mass.: �����Ƶ, 2018), 38.
• 57Ibid., 41.
• 58Notwithstanding considerable discussion within the Russian expert community over the last decade devoted to regional nuclear deterrence and the use of nonstrategic nuclear weapons to cope with conventional armed aggression, there is little evidence that this talk—some of it rather elaborate—has been translated into operational doctrine. The nuclear component in actual Russian military exercises neither figures as an early and key factor nor is it employed in limited, tactically precise fashion. In neither Zapad 2013 nor Zapad 2017, the large Russian war exercises in Russia and Belarus, were nuclear weapons employed in this fashion. The issue is well discussed in Dmitry (Dima) Adamsky, “If War Comes Tomorrow: Russian Thinking about ‘Regional Nuclear Deterrence,’” Journal of Slavic Military Studies 27 (1) (March 2014): 163–188.
• 59Lonnie D. Henley, “Evolving Chinese Concepts of War Control and Escalation Management,” in Assessing the Threat: The Chinese Military and Taiwan’s Security, ed. Michael D. Swaine, Andrew Yang, Evan Medeiros, and Oriana Mastro (Washington, D.C.: Carnegie Endowment for International Peace, 2007), 85–110.
• 60Fiona S. Cunningham and M. Taylor Fravel, “Dangerous Confidence? Chinese Views on Nuclear Escalation,” unpublished paper (2018), 4–5.
• 61The issue is discussed in Zhao and Li, “The Underappreciated Risks of Entanglement,” 57–59 and 63–65.
• 62Manoj Joshi, “The Credibility of ���Ի徱��’s Nuclear Deterrent,” in Krepon et al., Deterrence Instability, 55–56.
• 63Neil Joeck, “Prospects for Limited War and Nuclear Use in South Asia,” in Deterrence Stability and Escalation Control in South Asia, ed. Michael Krepon and Julia Thompson (Washington, D.C.: Stimson Center, 2013), 117.

Nearly all nine nuclear-armed states continue to gird themselves for the possibility that they could find themselves in a nuclear war, and, therefore, faced with the need to set goals and decide how to measure success or failure. If there is a common notion of what would constitute success, it is the vague sense of terminating hostilities on terms politically acceptable to one’s own side. But some countries fill that void more explicitly and elaborately than others.

The United States, for example, according to Roberts, has an emerging, although unarticulated, “theory of victory.”64 It assumes the principal threat facing the United States is a regional power willing to commit aggression despite U.S. conventional and nuclear superiority. Victory in this context is required even before hostilities begin, that is, against the risk of nuclear blackmail and brinksmanship. To achieve victory, the United States and its allies must have capabilities (conventional, collective, nuclear, and cyber) as well as resolve adequate “to prevent provocations, blunt attempts at provocation, and deter a decision to strike for a military fait accompli.” When hostilities begin, victory consists of inducing “the challenger to choose restraint over escalation when faced with military and political failure.” At this level, nuclear weapons may or may not be employed, but, if so, this should be in limited, precise, and proportionate fashion, relying on an adversary’s knowledge of U.S. superiority at higher levels of escalation to persuade him to call it quits. Failing that, if the war threatens to expand beyond the immediate war zone, victory would follow if the U.S. nuclear posture persuaded the adversary not to launch a nuclear attack on the U.S. homeland or that of its allies. What victory would look like in a war that falls between an adversary’s refusal “to choose restraint over escalation” and the point at which an adversary would be tempted to launch strategic nuclear strikes on the U.S. homeland, however, remains unspecified.

The trouble is that if Russia, China, and for that matter North Korea have a theory of victory or only a vague sense of what it might be, the premise of that victory is that in a war with the United States, it is the victim, not the one that started the war. For example, in the case of Russia, even if it believes nuclear use can be limited in a way that assures a Russian advantage in a war fought on its strategic perimeter, “victory” will not be achieved until the United States and/ or NATO relent. Presumably Russia, whatever the mounting cost, would continue to escalate the war, including its nuclear dimension. When approaching the threshold of a homeland-to-homeland nuclear exchange, the image of victory for Russia may simply be the obverse of that for the United States: namely, whatever the level of escalation in the war zone or broader military theater, the United States would be deterred from striking Russia with nuclear weapons for fear of what it would bring on itself.

In China’s case, presumably one route to war with the United States is through the United States’ defense of Taiwan or Japan in a military conflict between China and either one of them. Victory for China in this instance would doubtless be in preventing the United States from entering the conflict. If that failed, one assumes victory would be keeping the conflict regionally confined and below the nuclear threshold, with U.S. naval and air assets sufficiently degraded that the Chinese military could secure the leadership’s political objectives visà-vis Taiwan or Japan. Or conceivably, as some in the United States worry, it would be a successful quick-strike fait accompli, leaving the United States with no option short of putting its own regional bases and naval forces at risk.

Whatever the nature of thinking on war’s termination once nuclear weapons have been used, no matter how refined, it cannot escape the vagaries that surround the prior question: what to do if deterrence fails. Indeed, the whole subject grows more fraught because of three larger trends. First, renewed rivalry between the United States and Russia and potential strategic rivalry between the United States and China are rendering a serious military confrontation between them less an abstraction. Second, the development and refinement of conventional and nuclear military capabilities in all three countries are blurring the line between conventional and nuclear war, weakening the “nuclear taboo,” and resuscitating the notion of limited nuclear war. And, third, trends that mix politics, long-standing conflicts, and nuclear weapons are spilling out of bilateral relationships and into more complex trilateral configurations in ways that make it far more difficult to calculate what may happen when nuclear weapons enter the equation. Together they threaten settled assumptions about how nuclear competition is to be stabilized, how nuclear deterrence is to work, and how, if war comes, nuclear weapons are to be managed.

If that is true of relations among the United States, Russia, and China, the reality among other less established nuclear-armed states raises greater risks. In the case of India and Pakistan, clear thinking about the sequence of steps once a nuclear weapon is fired remains a well-kept secret, and how either envisages a war’s termination drifts into near desuetude. Pakistan, in the war games that it runs, expects outside powers to intervene and decide the outcome.65 India may have some hope a war can be terminated early and with limited damage, but if not, the screen conveying the defense planner’s thinking goes blank. In North Korea’s case, one can only guess with what assumptions the regime works. If Pyongyang believes war will come either because Washington decides to “bloody its nose” with a punishing conventional assault or impair its nuclear program by attacking test launch sites, it well may calculate that it can disrupt U.S. plans by preemptively attacking U.S. bases and military facilities in the region. Or in a war with South Korea, including one of its making, it may count on its ability to strike nearby U.S. air bases and ports and, at some point, the U.S. homeland with nuclear missiles as adequate to weaken U.S. readiness to get involved. In all cases, however, while the pathways to war between nucleararmed states are multiplying, the assumptions of these states, whether well curated or not, on how a nuclear war will unfold, let alone be controlled or ended, suffer the high likelihood of being wrong.

Endnotes

• 64Roberts, The Case for U.S. Nuclear Weapons, chap. 3.
• 65Tasleem, “Pakistan’s Nuclear Use Doctrine,” citing a communication with Feroz Hassan Khan, the former director of arms control and disarmament, in Pakistan’s Strategic Plans Division, Joint Services headquarters.

Predicting the future shape of the international political system, or where trends in a multipolar nuclear world may lead, or how one will affect the other is close to a fool’s errand. Surely, however, the dangers already present should be enough to impel a prudent person to imagine what could go wrong and to begin considering ways and measures that would spare the world from a nuclear reality more tenuous and hazardous than its Cold War predecessor.

Consider, for instance, the technological frontiers that the most advanced nuclear powers are crossing. Three technological clusters matter in particular: first, the continued effort to create effective ballistic missile defense, including so-called “left-of-launch” defense, exploiting cyber and directed-energy technologies; second, the development of conventional weapons capable of executing missions once reserved to nuclear weapons, including the destruction of nuclear weapons and their command-and-control systems; and third, advances in countries’ abilities to locate and track the other side’s strategic nuclear weapons. The continued development of a fourth technology also matters: the progress of several countries in lowering the yield of nuclear warheads and increasing the accuracy of the missiles delivering them—thereby lessening the collateral damage they do and the fratricide they risk—makes it more thinkable that they could actually be used.

Technology, as often observed, albeit not without contention, is a neutral factor. Its impact, for good or ill, in most cases depends on the use to which it is put. Sorting that out in the case of these four technological areas, however, is not easy. Advances in any one of them could contribute to a more stable nuclear environment or, alternatively, could considerably heighten the danger that in a crisis—or simply as the result of an accident—nuclear weapons will be used. Whether their impact is one or the other depends, first, on the purpose to which they are put; second, the degree to which they are developed and on what scale; and, third, whether their incorporation is on a mutually understood and accepted basis by potential adversaries.

The U.S. effort to develop a fleet of new weapons, such as the new B-61 nuclear gravity bomb with a tail section and steerable fins that allow a vast advance in accuracy and controlled collateral damage, a modified nuclear warhead for ballistic missiles whose fuze system also improves accuracy with lower yields, and a proposed new low-yield warhead for Trident II D5 SLBMs, is designed to enhance “tailored deterrence” by giving the president “a range of limited and graduated options, including a variety of delivery systems and explosive yields.”66 No doubt a comparable rationale exists on the Russian side for developing the new submarine-launched nuclear-armed Kalibr cruise missile, the 9M729 ground-launched cruise missile (said to violate the Intermediate-Range Nuclear Forces [INF] Treaty), and the nuclear version of the Iskander sub-strategic missile. The usability of these weapons, advocates argue, makes nuclear deterrence more credible, and, hence, reduces the likelihood of war. But in a war this same quality increases the likelihood of their use. How countries balance this trade off—if they do so—will determine how stabilizing or destabilizing this technology is. As a result, in order to be stabilizing this technology cannot be allowed to run free. Governments will need to decide how slippery they want the slope into nuclear war to be versus how plausible they insist their readiness to use nuclear weapons must be to ensure nuclear deterrence, and then reach some understanding of how much and in what form of this capability, if any, they require.

The same can be said of ballistic missile defense (BMD). If, for the moment, none of the five countries with BMD programs has a system fully capable of defending against a large-scale strategic nuclear attack, progress toward thicker, integrated systems will at some point call into question the adequacy of countries’ capacities for inflicting assured destruction in a second strike. It already does for countries with limited nuclear forces. Technologies moving beyond current capabilities loom on the horizon. The United States intends to deploy a new technology called a Multi-Object Kill Vehicle (MOKV) that allows a single interceptor to destroy multiple incoming objects, including decoys. It appears designed to deal with Russian and Chinese MIRVed missiles, not the more primitive threat U.S. officials insist is the purpose of the United States’ current missile defense program.67 The United States also has underway a major new research effort to develop so-called “left-of-launch” defense, an approach employing non-kinetic tools—such as electromagnetic pulse attacks and airborne lasers—to disable computers and sensors controlling an opponent’s missile systems, paralyzing or destroying these weapons before they can be launched.68 And, as noted earlier, thoughts of a space-based ballistic missile defense system are again in the air. The Russians and the Chinese are developing similar technologies.

Ballistic missile defense could be a stabilizing factor in two circumstances: First, if and only at the point peer rivals have a fully effective BMD system guaranteeing their safety against a nuclear attack at any level. (Short of that, in an offense-defense competition and with imperfect BMD on one or both sides, the effect will surely be destabilizing.) The second stabilizing case would be an agreement to limit BMD to something short of a threat to a peer opponent’s assured retaliatory capability, but this raises two problems. On the one hand, limited BMD that protects against limited nuclear attack, if effective, will undermine the nuclear component in tailored deterrence—i.e., the feasibility of a limited use of nuclear weapons. On the other hand, when directed at third parties, such as North Korea or potentially Iran, peer rivals will treat it as threatening to them. This is also true with the Terminal High Altitude Area Defense (THAAD) and Aegis systems deployed by the United States in East Asia, but viewed by China as also targeting it.

Another area in which technological advances impinge on crisis stability involves nonnuclear technologies, principally advanced conventional strike forces and ASAT weapons. The first category includes primarily hypersonic cruise missiles and hypersonic boost-glide vehicles. Their potentially destabilizing qualities center on their ability to deliver conventional or nuclear warheads against conventional or nuclear targets and on their ability to escape detection after early warning. Once launched, the uncertainty they create over payload, location, and destination invites misinterpretation and inadvertent escalation to nuclear war.69 While it is difficult to envisage ways in which large numbers of these weapons available to peer rivals can be stabilizing, if they are to be rendered less destabilizing, it would presumably be by limiting their numbers. Retained for prompt long-range conventional missions, say, against a terrorist group planning an attack with biological or chemical weapons, their effect would be one thing. If they come to have a nuclear counterforce mission, their effect will be quite another.

The ASAT issue leads quickly to the problem of entanglement, particularly in the U.S.-Chinese context. China’s vigorous efforts in this area, as noted earlier, may be principally intended to give it the option of disabling U.S. spacebased reconnaissance and communications satellites early in a limited conventional war—but in the fog of war, because these same satellites are key to the U.S. early-warning nuclear system, U.S. leaders might well misread this as a prelude to a nuclear attack. The danger swells, if, as Chinese observers maintain, the Chinese side is sure that the United States, aware of China’s no-first-use posture and confident its leadership would not commit nuclear suicide, could not make this mistake. In this case, it is difficult to conceive how the pursuit of ASAT weapons by any of the key parties can contribute to crisis stability. To the extent that these weapons are pursued, crisis stability will depend on the measures states take to harden their early-warning systems and provide them with redundancy.

Finally, advances in a wide range of converging technologies that, if perfected, were capable of locating and tracking in real time mobile ICBMs and sea-based strategic nuclear forces could be stabilizing or destabilizing in multiple and complex ways. The panoply of relevant technologies extends from aerial reconnaissance, including drones, to space-based imaging; from cyber, artificial intelligence, and machine learning to data analytics. In a futuristic stable nuclear world, they, in effective combination, would be essential to foolproof BMD. Were they, in an initial stage, only able to compromise mobile ICBMs, from one perspective, this could be seen as stabilizing, to the extent that states were impelled to abandon ICBMs, the most vulnerable segment of the triad, and rely on the more secure sea-based portion of their deterrent when fully developed. Or its effect could be destabilizing, if states feared that a cornerstone of their nuclear deterrent was now vulnerable to a disarming first strike. Were these technologies, in combination with ASW weapons, such as unmanned underwater vehicles, electronic barriers, and underwater gliders, able to threaten SSBNs, viewed as the anchor of a secure second-strike capability, the destabilizing impact would be indisputably immense.

All this said, the critical fact is that most of these technologies have not yet arrived. True, those being pursued in virtually all critical nuclear realms by all major nuclear players raise doubts whether the United States and Russia, in particular, really are reconciled to living with mutual vulnerability as a basis for strategic stability.70 It may be that MAD came to be accepted in the U.S.-Soviet nuclear relationship more as a reality than a doctrinal choice, simply because technological limitations dictated it. If they no longer do, and some nuclear states have set themselves the goal of overcoming it, what then is the basis of strategic nuclear stability in this new multipolar nuclear age?

On the other hand, if in a world of nine nuclear powers and the mounting complexities this world is generating, key states want to head off the destabilizing effects that lie on the other side of the technological frontiers they are approaching and concentrate on ways that the advance of technology can be made stabilizing (not merely advantageous to one side), now is their chance. If they wish to be architects of their future and not simply caught in the current of events, the elements with which they would be working are still forming.

Technology, however, is but one piece of a puzzle whose other pieces are also in motion. Rather than, as during the Cold War, when two states gradually embraced a common notion of strategic stability and underwrote it with an arms control agreement (the Anti-Ballistic Missile [ABM] Treaty), the notion of strategic stability is gradually losing cohesion as the premises underpinning multiple states’ concepts of nuclear deterrence drift apart.71 Nor do prospects favor a conscious effort to manage the untoward direction that nuclear trends might take, given the demise of nuclear arms control and the weakening of nuclear norms, including the nuclear taboo.72 Add to this the complications in framing arrangements that cope with the challenges posed by many states at different levels of nuclear development, with incommensurate capabilities, and in often widely different threat environments.

Finally, trends in the larger geopolitical setting form the ultimate arbiter of what happens among the nine nuclear-armed states and whether their world skids into trouble or finds some level of stability. This has two dimensions: the first is structural—that is, not merely the proliferation of nuclear-armed states, but the ambitions of China and India to be, and to be treated as, global powers, along with Russia’s determination to reclaim the political status that reflects its nuclear prowess. For India and China, their nuclear profile now transcends that of regional secondary nuclear actors. They want to be seen as equals by peer rivals, and their field of rivalry now has an increasingly elaborate nuclear dimension. For Russia, whatever the deficits in the other sources of its power, the fact that it still has nearly half of the world’s nuclear weapons and is modernizing them ensures it will remain a decisive player in shaping a multipolar nuclear world, however it chooses to play that role.

The second dimension is dynamic and reflects a central theme of this essay: trends in political relations among the major nuclear powers ultimately determine the meaning of the nuclear choices those states are making and the effect they will have. When U.S.-Russian relations are spinning in reverse, as they are now, the prospect that the two countries, or they with others, will join together to address any of the challenges discussed in this essay is dim to nonexistent. If relations were to worsen further, many of the factors threatening crisis stability in this new nuclear era would acquire greater force, especially if U.S.-Chinese relations turn adversarial, as recent newspaper headlines suggest they could.73  Thus, as significant as the evolution from a bipolar to a multipolar nuclear world may be, as complex and fraught are the implications of the technological barriers that nuclear powers are crossing, and as vexing and potentially dangerous is the cacophony of concepts and strategies guiding nuclear thinking among them, how well the major nuclear states, beginning with the United States and Russia, manage their overall relationships will determine how well they manage the challenges of this new nuclear era.

If the larger geopolitical scene were less forbidding and if governments were ready to resume their efforts to control the pace and scale of the nuclear change underway, the task facing them would nonetheless be considerably more complex than what confronted the United States and the Soviet Union during the Cold War. Given the number and diversity of nuclear actors, the range of technologies implicated, and the asymmetries in countries’ capabilities, doctrines, and postures, a single process among states seeking a comprehensive agreement is manifestly impossible. Progress, if achieved, will doubtless be fragmented and multifaceted—a montage of agreements, some formal, some informal, between different combinations of states. And it will be uneven, dealing with different parts of the problem in no particular sequence, producing a slow, choppy cumulative effect.

For anything to happen, however, the key nuclear actors, beginning with Russia and the United States and at some early point China, must first pause, take a step back, and reflect both on the potential dangers in the weapons choices they are making as well as on weapons choices that could contribute to a more stable nuclear environment. They need to engage one another and do so at various levels: bilaterally in most cases; trilaterally—the United States, Russia, and China, or India, Pakistan, and China—in others; all five countries together on issues that transcend these narrower contexts; and, for some purposes, such as deliberating over nuclear norms and basic concepts, all nuclear-armed states would need to be involved.74 Strategic dialogue of this kind is most difficult in the circumstances when it is most needed. At the same time, however, engaging in this fashion, especially if it is productive, not only opens a path for dealing with the challenges of a new nuclear era, but it helps to ease the tension in deteriorated or deteriorating relationships. Though the odds that governments will rise to this challenge remain low, the conversation needs to begin among experts in the nuclear weapons states.

Endnotes

• 66Nuclear Posture Review, 2018, 31.
• 67Kris Osborne, “Get Ready, Russia and China: U.S. Missile Defense Is Going ‘Star Wars,’” National Interest, May 17, 2016, .
• 68Bill Gertz, “Pentagon Developing Pre-Launch Cyber Attacks on Missiles,” Washington Free Beacon, April 14, 2016, .
• 69James M. Acton, Silver Bullet? Asking the Right Questions about Conventional Prompt Global Strike (Washington, D.C.: Carnegie Endowment for International Peace, September 2013).
• 70Not that they ever were entirely. James M. Acton, “Reclaiming Strategic Stability,” in Strategic Stability: Contending Interpretations, ed. Elbridge A. Colby and Michael S. Gerson (Carlisle, Pa.: U.S. Army War College Press, 2013), 144–145, notes how many authors have shown that, despite official declaratory policy, the United States resisted living with mutual vulnerability and continued to pursue a war-winning strategy during the Cold War. The most recent study to explore the subject is Caroline R. Milne’s Ph.D. dissertation, “Hope Springs Eternal: Perceptions of Mutual Vulnerability Between Nuclear Rivals,” The Woodrow Wilson School, Princeton University, November 2017.
• 71Not to overstate the contrast, Alexei Arbatov reminds us of the gap that always remained between U.S. and Soviet nuclear thinking in “Challenges of the New Nuclear Era,” 21–46.
• 72Nina Tannenwald, “The Great Unraveling: The Future of the Nuclear Normative Order,” in Jane Vaynman, Nina Tannenwald, and James M. Acton, Meeting the Challenges of the New Nuclear Age: Emerging Risks and Declining Norms in the Age of Technological Innovation and Changing Nuclear Doctrines (Cambridge, Mass.: �����Ƶ, 2018).
• 73For example, Jane Perlez, “Xi Jinping Extends Power, and China Braces for a New Cold War,” The New York Times, February 27, 2018.
• 74I have attempted to sketch the issues that need to be addressed and the formats in which they might be addressed in Robert Legvold, “The Future of Nuclear Arms Control,” Topical Issues of Nuclear Non-Proliferation, ed. Viatcheslav Kantor (Geneva: The International Luxembourg Forum on Preventing Nuclear Catastrophe, 2018), 26–49.