The Case for U.S. Nuclear Weapons in the 21st Century
Brad Roberts



The United States is entering a period of renewed debate about nuclear deterrence. That debate will address the most fundamental question: Are U.S. nuclear weapons merely Cold War relics that belong in “the dustbin of history” along with communism and the Soviet Union, or do they make an important and irreplaceable contribution to the national security of the United States?

This debate will be driven by three key factors. The first is the reassessment of U.S. defense strategy after fifteen years of war in Afghanistan and Iraq. A number of questions come into play. Is a shift away from counter-terrorism and counter-insurgency possible for U.S. military planners? Is the intended “rebalance” of security strategy toward Asia possible given widespread instability in the Middle East and Russian assertiveness in Europe? Is limited war with China and/or Russia a serious possibility? Is war with North Korea likely; if so, how might it exploit its new military capabilities to try to secure its interests? Will Iran “go nuclear” and with what implications for U.S. military strategies? What can the United States do to constructively shape developments in the Middle East while insulating itself and its allies and partners from the effects of deep and sustained conflict there? Answers to each of these questions have important implications for U.S. nuclear policy and posture.

Developments in the security environment that call into question some of the premises of U.S. policy since the end of the Cold War also play a role in driving renewed debate. The profound changes in Russia’s foreign policy in 2014 have raised fundamental questions about the future role of nuclear weapons in Europe and in U.S.–Russian relations more generally. North Korea’s progress in developing weapons capable of reaching the United States highlights an emerging major challenge to U.S. security strategy. China is making significant progress in deploying the key elements of a secure nuclear retaliatory force. Some U.S. allies in Europe, Asia, and the Middle East feel pressured by these developments and are seeking new forms of assurance that the U.S. security commitment to them will remain credible over the long term. New premises might well drive U.S. nuclear policy in new directions.

In addition, policy makers in Washington need to decide whether and how much to invest in keeping U.S. nuclear forces viable. For the last twenty-five years or so, the United States has spent only the money needed to operate and maintain standing nuclear forces. It has not had to modernize or replace them. Over the next twenty-five years or so, the entire remaining triad of delivery systems and inventory of weapons will have to be modernized or replaced in some way. These will be inherently contentious decisions, not least because they come at a time of budget austerity and in competition with the need to renew nonnuclear forces after more than a decade of war in Iraq and Afghanistan.

But the United States is ill prepared for this debate. Most of the stakeholders in the debate about U.S. nuclear deterrence policy and posture made up their minds a long time ago about the big questions. They generally fall into two camps with different core beliefs.

One camp recoils from the horror of nuclear war, sees the risks of nuclear terrorism as high, seeks the abolition of nuclear weapons, and advocates strongly for steps by the nuclear weapons states toward that end. It places a particular onus on the United States to take additional substantial steps at this time to reduce its reliance on nuclear weapons and otherwise lead by example. It makes a passionate case against nuclear weapons and for disarmament.

The other camp accepts nuclear weapons as necessary and useful, sees risks from both states and nonstate actors, and advocates for retention of U.S. nuclear forces sufficient to U.S. military and political purposes. It rejects the notion that abolition would make the world a safer place. It resists continued steps to marginalize nuclear weapons in U.S. security strategy. Its case for nuclear weapons is pragmatic but not passionate in the way of the disarmers.

These two camps do not debate each other so much as they pursue competing agendas. Though there are examples of respectful discourse between them, adherents of each camp are generally contemptuous of the views of the other. Given the long-standing and deep divisions between these two camps, agreement on policy is rare.

One practical result of this divergence has been gridlock in Congress, which has found it difficult to produce decisions in support of any particular nuclear policies. Looking for a way out of this gridlock, in 2007 Congress created a commission, with an equal mix of Democrats and Republicans, and essentially asked it two simple questions. Is there any basis for a renewal of bipartisanship sufficient to sustain U.S. nuclear policy over the longer term? If so, what is it? Despite strong differences of opinion on many matters, members of the Strategic Posture Commission converged on a hopeful note. Policy continuity is possible, they argued, on the basis of a balanced approach that combines political efforts to reduce and ultimately eliminate threats with military efforts to deter existing threats.

Seven years later, a third camp has not coalesced around this balanced approach. This is so despite the fact that the Obama administration embraced this approach and used it as a guide in developing and implementing its nuclear policy. Adherents of the other two camps sometimes praise the virtues of the balanced approach, but rarely are such words followed by deeds of advocacy in support of policy initiatives that depart from the canon of their camp.

This book will not remake these fundamental contours of the U.S. debate on nuclear policy and posture. But it can help to inform the coming debate and to shift it onto more productive grounds. Toward this end, it has a number of objectives.

One is to review and assess the experience of the Obama administration in working to create the conditions that would allow the United States and other states with nuclear weapons to take additional steps in the future to reduce the role and number of such weapons. The administration has made a serious, sustained, and high-level effort toward this end. Yet, despite some important achievements, the overall results are disappointing. The lessons are many.

A second objective is to review and assess the experience of the Obama administration in working to adapt nuclear deterrence to 21st-century purposes. Having declared that nuclear deterrence should be effective so long as nuclear weapons remain, President Obama directed the Department of Defense to ensure that nuclear deterrence will be effective for the problems for which it is relevant in the 21st century. This work has revealed important insights into the particular new challenges of regional conflicts under the nuclear shadow, of extended deterrence, and of strategic stability. The lessons here, too, are many.

A third objective is to review and assess the “balanced approach.” The Obama administration has made a good faith effort to implement this approach even as the world around it has changed in significant and worrisome ways. Does it remain valid? If so, what does it require, and what will it require of future administrations?

A final objective is to fill a key gap in the current debate. As it now stands, the case made for U.S. nuclear weapons is not robust. It stands on assertions about the enduring value of nuclear weapons in preventing major power war. Whether nuclear weapons will continue to be effective in preventing limited wars among major powers is an open question. Moreover, this case lacks the fidelity needed to determine which capabilities are needed. This book sets out a somewhat different case for U.S. nuclear weapons, drawn from the preceding analysis.

In support of these objectives, this volume proceeds as follows. It begins with a more complete characterization of the current debate about U.S. nuclear policy and posture than possible in this introduction. Chapter 1 reviews the evolution of U.S. nuclear policy and posture from the end of the Cold War to today, highlighting elements of both change and continuity. It also reviews relevant developments in the external analytical and political communities with an eye to understanding their influences on the policymaking process.

Subsequent chapters explore U.S. efforts to adapt deterrence to 21st-century purposes and to bring into being the conditions necessary to safely take further steps to reduce the role and number of nuclear weapons. Chapter 2 turns to the new strategic problem posed by the proliferation to regional actors like North Korea of nuclear weapons, other weapons of mass destruction, and the long-range missiles to deliver them. I call this “the first new strategic problem” because it is without precedent in the Cold War and because it took shape before some newer problems for the U.S. strategic posture.

This chapter develops a heuristic device for understanding the deterrence challenges for the United States posed by a nuclear-armed North Korea and perhaps by other nuclear-armed regional challengers in the future. It sets out a spectrum of deterrence challenges from the lowest to the highest ends of conflict. This spectrum helps to illuminate the possible ways in which such a conflict might escalate and deescalate and thus the decision points that the United States will want to influence with an eye to inducing adversary restraint.

To better understand how potential U.S. regional adversaries might think about their escalation and deescalation strategies in conflict with the United States, this chapter invokes an old, contentious, but still useful term: theory of victory. For historians of nuclear deterrence, this term conjures up Cold War debates about whether leaders in the Soviet Union actually believed that general war involving the large-scale use of nuclear weapons could be fought and won (or believed that a general war in Europe could be fought and won without crossing the nuclear threshold). It also invokes debates about whether the United States could or should have had such a theory during the Cold War. Those are important debates, but they attach a particular meaning to the term that is uniquely associated with the Cold War.

Today, the term is useful for coming to terms with the thinking done by potential U.S. adversaries about how to manage the risks of escalation against a militarily superior foe and otherwise to secure their interests when in conflict or confrontation with the United States. It is difficult to find solid evidence that any such potential adversary believes that it can fight and win a major nuclear war against the United States. But there is some evidence that such potential adversaries have developed nuclear theories of victory over the United States in two senses. The first is in the Clausewitzian sense (in which war is a continuation of politics by other means, and thus victory is a “culminating point” in war when one side chooses to accept an outcome on political terms dictated by the other rather than bear the costs and risks of continued war). The second is in the sense of Sun Tzu (in which war is a failure of policy, and thus victory entails subduing the enemy without fighting).

There is good reason to be skeptical about the theories of victory being developed by potential U.S. adversaries and the available evidence. After all, the leaders of states fearful of U.S. military intervention must convey to U.S. leaders their intentions and capabilities to stand up to the United States. This is a domestic political requirement for them and may also have some international benefits. Moreover, the existing evidence is piecemeal, incomplete, and of varying degrees of credibility. It is difficult to assess whether the available evidence reflects coherent and complete military doctrines and political strategies or instead reflects a mix of wishful thinking and propaganda. Accordingly, it is important to let the evidence speak for itself and to resist knitting together a military logic for nuclear war that political leaders of these countries might find difficult to embrace.

But the cumulative body of available evidence sends a strong message: that a few potential adversaries have thought in a serious and sustained way about conflict with the United States under the shadow cast by nuclear weapons, both theirs and ours. They may believe that they can engage in nuclear coercion and blackmail and that, in extremis, they could resort to nuclear employment and escape conflict with the United States with some of their main interests intact. The United States would be ill served by simply waiting for more evidence. Even as we look for more such evidence, we must begin to come to terms with their potential theories of victory. Our historical experience of nuclear war as unthinkable should not blind us to the possibility that it has been made thinkable for the leaders of countries with a different historical experience and a different strategic problem. After all, history is replete with adversaries acting in ways we see as irrational in light of their interests as we understand them. Their nuclear aggression might seem suicidal to us, and thus implausible, but it might in extremis seem to them to be a risk worth taking to secure regime survival or some other core interest.

Accordingly, Chapter 2 makes the case that there is evidence, albeit imperfect and incomplete, that North Korea’s leaders have a small number of nuclear-backed theories of victory. The term is then invoked again in the subsequent analyses of Russia and China, not to suggest that they have nuclear strategies akin to the Soviet Union but to explore their thinking about how to exploit the shadow cast by their nuclear weapons to avoid war with the United States and to prevail if war proves unavoidable. To encompass the thinking of multiple potential U.S. adversaries about this problem, I sometimes refer to “Red theories of victory” as a shorthand.

Chapter 3 sets out the response of the United States to the new strategic problem posed by regional challengers armed with nuclear weapons and long-range delivery systems. It characterizes a continued but changed role for U.S. nuclear weapons in meeting these new challenges in the context of a comprehensive approach to adapting and strengthening regional deterrence architectures. This chapter also sets out a “Blue theory of victory”—another shorthand, in this case encompassing a set of hypotheses about how the United States can manage escalation and deescalation in a confrontation with a nuclear-armed state in a manner that safeguards its interests. This Blue theory, like its Red counterparts, has elements of both Clausewitz and Sun Tzu, in that it is about achieving U.S. objectives in peacetime as in crisis and war. The formulation offered here is the author’s and relies on the heuristic device from Chapter 2 (the spectrum of deterrence challenges) to map out the problem space.

The book then turns to the U.S. relationships with Russia and China, in Chapters 4 and 5 respectively. The analysis highlights the similarities and differences between these two cases, not least in terms of their impact on U.S. nuclear policy and posture. Chapter 4 on Russia reviews more than two decades of effort by leaders in both Washington and Moscow to move the bilateral relationship in a positive new direction and the sharp turning point in Russian policy in spring 2014. Chapter 5 on China reviews the parallel history in the U.S.–China relationship and the potential for a future turning point in Chinese policy. The Obama administration has put the spotlight on strategic stability as the organizing concept for the nuclear relationship with both countries, as a counterpoint to a spotlight on deterrence. It has encountered myriad challenges in advancing an agenda to strengthen strategic stability with both countries.

Relations with U.S. allies in Europe and Northeast Asia under the so-called nuclear umbrella are the focus of Chapters 6 and 7 respectively. Extended deterrence is the provision of nuclear-backed security guarantees to U.S. allies (more precisely, to a select group of them). The changed and changing requirements of extended deterrence have been little studied in the United States with the passing of the Cold War. Yet the United States continues to provide security guarantees to more than forty allies in three regions (Europe, Northeast Asia, and the Middle East), and some of them feel strongly pressured by new developments in their security environments, whether those be the ambitions of a newly nuclear-armed neighbor (as in Northeast Asia) or uncertainty about the strategic intentions of a neighboring major power (as in both Europe and Northeast Asia). Some of these allies have returned to fundamental questions about whether the United States is a credible guarantor of their security, especially their security from nuclear threats.

Chapter 8 summarizes the key insights from the preceding two chapters as they bear on the question of the assurance of allies. It invokes the so-called Healey theorem (in reference to a former British defense minister) to the effect that assuring allies that they will escape coercion, aggression, and the costs of war is more politically challenging than deterring potential adversaries. It does so to set out an assessment of the current state of assurance of U.S. allies under the U.S. nuclear umbrella.

This chapter also challenges the reader to think more broadly about the assurance requirements of U.S. nuclear strategy. Other actors require assurance of various forms—including U.S. allies and partners not under the nuclear umbrella, other states that foreswore the right to nuclear weapons when they joined the Nuclear Non-Proliferation Treaty (NPT), even U.S. enemies (who require a unique form of assurance for our deterrence strategies to function as desired). This chapter also considers the unique challenges of assuring the three major powers—the United States, Russia, and China—that their strategic restraint will not be exploited by another power. The chapter concludes with the argument that its possession of nuclear weapons helps to assure the United States that the risks and burdens of international leadership are bearable.

Chapter 9 sets out my conclusions from this work. It draws on the lessons of the Obama administration and its predecessors, as distilled in the intervening chapters, in adapting U.S. deterrence strategies to new circumstances and in trying to create the conditions to (1) make additional substantial changes to the number of nuclear weapons in the U.S. arsenal and to their role in U.S. security strategies and (2) enable other nuclear-armed states to join with us in future steps. Here I argue that the time is not ripe for additional substantial changes. Quite simply, other states are not prepared to join us at this time in such steps, and additional unilateral action would serve the United States poorly.

This argument culminates in a restatement of the case for U.S. nuclear weapons. It derives from the lessons noted in the preceding pages and from the requirements of the Blue theory of victory in both crisis/war and peacetime. It does not contradict the existing case for nuclear weapons. It adds fidelity and amplification drawn from the current security context and in a way that informs choices about needed U.S. capabilities. Significantly, it is not a case for nuclear weapons in perpetuity. Looking twenty-five or fifty years into the future, there is no reason to preclude the possibility of changes in the security environment that could substantially reduce the need for U.S. nuclear weapons. But neither can they be assumed today.

The closing chapter considers implications. This epilogue returns to the opening chapter and asks, “Where do we go from here?” in light of the conclusions and lessons learned. It poses some basic questions about whether the approach to nuclear policy and posture in place since the end of the Cold War still makes sense in today’s world and considers potential adjustments.

This short summary of the scope and structure of the book invites a clear statement about what the book is not: It is not a book about every aspect of U.S. nuclear policy and strategy. It does not address a variety of questions that are important but unrelated to questions of U.S. nuclear deterrence policy and posture. What more can be done to strengthen the nonproliferation regime? What more can be done to reduce the risks of nuclear terrorism? What might be the specific elements of a future U.S.–Russian arms control agreement? What should the United States do about the emerging nuclear competition in South Asia? How can it prevent a nuclear tipping point from being crossed in Northeast Asia and the Middle East? Should it try to sustain cooperative threat reduction activities with Russia? How might it expand them with others? These topics belong in any comprehensive discussion of U.S. nuclear policy and strategy, and the argument laid out in this book has implications for many of those questions. However, the focus here is on the key determinants of U.S. deterrence policy and posture.

Nor is this book a comprehensive analysis of all of the conditions that would have to be fulfilled to allow the United States to safely proceed to eliminate its nuclear weapons. A full catalogue of the conditions that would have to be brought into being would include, for example, confidence in a system of international monitoring and compliance enforcement that could be counted on to deal with any aggressor caught surreptitiously producing nuclear weapons. Examining these further conditions is beyond the scope of this volume.1

As an analysis of U.S. nuclear policy and posture, this volume draws on my experience in the Obama administration, where I played a leading role in the preparation and implementation of the administration’s Nuclear Posture Review as deputy assistant secretary of defense for nuclear and missile defense policy. But it also reaches well beyond this governmental experience, by drawing on insights gained in many years of work as an analyst in the Washington think-tank community. Where I describe and characterize administration policy, I am explicit in doing so. Where I go beyond official policy to amplify or extend ideas with thinking of my own, I do so explicitly. The views expressed here are my personal views and should not be attributed to the Obama administration, the U.S. Departments of Defense and Energy, Stanford University, or any institution with which I have been or am affiliated.


1. Michael May, “The Trouble with Disarmament,” Bulletin of the Atomic Scientists, Vol. 64, No. 5 (November/December 2008), pp. 20–21.