Book Review: Posture Matters, but Stability Matters More

Reviewed by Douglas B. Shaw

Nuclear Strategy in the Modern Era: Regional Powers and International Conflict
By Vipin Narang
Princeton University Press, 2014, 360 pp.

Vipin Narang’s new book, Nuclear Strategy in the Modern Era: Regional Powers and International Conflict, is an important step forward in understanding the emerging global landscape of nuclear weapons policies that could point in a dangerous direction. The book fills a gaping hole in the literature on nuclear weapons by offering a plausible explanation for why new nuclear states choose the nuclear postures that they do.

It also demolishes the common assumption that possession of a nuclear weapon provides deterrence. Narang deploys sophisticated quantitative methods to demonstrate that the ability to deter conventional attack varies with the nuclear postures that states select. In so doing, Narang’s argument could encourage states to consider more-aggressive nuclear postures.

Narang, an associate professor of political science at the Massachusetts Institute of Technology (MIT) and a member of the school’s Security Studies Program, improves scholarly understanding of 21st-century nuclear strategy in several additional ways. He has chosen an important, policy-relevant topic for academic research; challenged entrenched biases; categorized emerging nuclear postures; rigorously observed the reasons that states choose their nuclear postures and the effect of these posture choices on international conflict; described the specific nuclear postures of several states; and, one hopes, provided the spark for a wider scholarly consideration of nuclear policy. He concludes that aggressive, first-use nuclear postures deliver unique deterrence benefits below the threshold of nuclear weapons use, a finding that should be considered within the context of the inherent risk of such postures.

Narang’s choice of topic is noteworthy for a couple of reasons. First, his work delivers new concepts and insights that may prove immediately useful to policymakers. This is unusual because policy relevance is strangely unnecessary for success in political science. Second, the topic of nuclear weapons policy has grown unpopular in the academy. Narang reports that “almost everyone…was telling me the subject was dead.”

Narang goes against the grain in both respects and identifies a troubling, important issue: “[t]he effect of nuclear weapons on deterring conflict remains fundamentally unclear.” Given the prospective effect of deterrence failure on international conflict, the dangers of inadvertent or unauthorized use of nuclear weapons, the destructive potential of nuclear weapons, and the security, economic, and human costs of maintaining nuclear arsenals, this is a public policy consideration of the first order.

Narang applies rigorous analytical methodologies to the topic of nuclear posture—the forces, doctrines, plans, and rules for the use of nuclear weapons. He confronts problems in the literature such as a “Cold War hangover” of overemphasis on the experience of the superpowers with nuclear deterrence and an “existential bias” characterized by “focusing almost exclusively on a state’s acquisition or test of its first nuclear weapon.” He contends that his findings “fundamentally challenge the assumption that the mere possession of nuclear weapons provides substantial deterrence benefits.”

He proceeds to offer three “mutually exclusive and empirically exhaustive” categories of nuclear postures into which he sorts the practices of non-superpower nuclear-armed states. These are “a catalytic strategy that attempts to catalyze superpower intervention on the state’s behalf; an assured retaliation strategy that threatens certain nuclear retaliation in the event a state suffers a nuclear attack; and an asymmetric escalation strategy that threatens the first use of nuclear weapons against conventional attack” (italics in original). This useful contribution provides an intuitive and descriptive shorthand for discussing these postures and their relative merits.

Narang’s “posture optimization theory” describes the conditions driving states to select among the three postures he defines. According to Narang’s theory, four sequenced variables about a state with nuclear weapons allow an observer to predict the state’s nuclear posture. If the state perceives “the availability of a reliable third-party patron” to guarantee its security from aggression, it will select a catalytic nuclear posture to reinforce that positive security assurance. If no powerful patron is available and a state faces a “conventionally-superior proximate offensive threat,” Narang’s theory predicts that the state will adopt an asymmetric escalation nuclear posture. If the state has neither a powerful patron nor a threatening neighbor with superior conventional forces, then Narang expects its nuclear posture to depend on its “civil-military arrangements.” He distinguishes between two types of these arrangements: “assertive,” in which civilian political authorities exercise tight control over the military, and “delegative,” in which the military enjoys wide freedom of action in questions of defense policy.

Narang theorizes that assertive civil-military arrangements favor a nuclear posture of assured retaliation while delegative civil-military arrangements leave a state’s choice of nuclear posture open to the question of resource constraint. If such a state has the money, it may choose asymmetric escalation; otherwise, Narang predicts, it will choose assured retaliation. Narang assumes an asymmetric escalation posture to be more expensive than an assured retaliation posture. This assumption is intuitively attractive because historical experience suggests that changing to an asymmetric escalation posture requires more and more-diverse nuclear forces. Yet, by not quantifying this difference in expense or exploring the possible advantages of more-expensive variants of assured retaliation, Narang leaves a door open to additional research.

Narang demonstrates the superior explanatory power of his theory against three alternatives across six empirical cases. Narang’s first alternative explanation for nuclear posture is structural realism, relying on the distribution of power in the international system. Technological determinism, in which a state’s capabilities determine its nuclear posture, is Narang’s second alternative. In describing it, he misses an important opportunity to recall the crippling blow that his MIT security studies faculty predecessor, the late Stephen Meyer, dealt to this idea in his 1986 book, The Dynamics of Nuclear Proliferation,[1] and the persistent nonproliferation puzzle of states that have the technical capability to acquire nuclear weapons but have not done so. Finally, Narang evaluates strategic culture, finding it to be an intervening variable—a factor that exerts influence through another factor—by influencing nuclear posture “through a state’s civil-military relations.” He finds that the observed nuclear postures of states in his case studies are more reliably aligned with his posture optimization theory than with any of the three alternatives and that his theory offers additional insight into when states may choose to change their nuclear postures. On this basis, Narang argues that posture optimization theory will predict future posture decisions of regional nuclear powers.

Rich with careful observation and historical context, the six case studies augment the importance of this book for any reader interested in nuclear policy. These chapters concentrate and explain the findings of a voluminous secondary literature on each case, making the book a useful and convenient primer on contemporary nuclear strategy, even for readers who might not have great interest in the book’s discussion of Narang’s research methods. For those readers, however, the methodologically driven exclusion of the United Kingdom and North Korea from the list of cases explored is frustrating.

Historical perspective on U.S. nuclear posture during the Cold War would also be interesting to explore in parallel. Nonetheless, the six case-study chapters—Pakistan, India, China, France, Israel, and South Africa—constitute a thought-provoking vehicle to explore the drivers and characteristics of nuclear posture as a globalizing phenomenon.

Narang argues that the states he studies “enjoy” a “reduction in armed conflict at every level of intensity, compared to both non-nuclear states and states that adopt other nuclear postures” only when they exhibit an asymmetric escalation nuclear posture. This finding is important and troubling. In claiming to overturn a widely held assumption that the mere existence of nuclear weapons provides deterrence, Narang’s work seems to raise the prospect that this discovery will prompt more states to adopt more-aggressive nuclear postures. This might be dangerous. The unique benefits of asymmetric escalation postures may not persist if these benefits are more widely understood and additional states seek them by adopting asymmetric escalation postures, upsetting existing dyads and perhaps more-complex deterrent relationships. He wisely observes that “this posture undoubtedly carries with it other significant risks, such as severe command-and-control pressures and an attendant increase in the risk of inadvertent nuclear use.”

Acknowledgment of this danger begs for more research to understand, in Narang’s terms, when states should “trade off some ‘deterrent power’ for arsenal security.” The prospect of deterring conventional or terrorist attack will be attractive to many, possibly leading some nuclear states to undervalue security against the prospect of inadvertency. Overturning widely held assumptions may itself be dangerous, even if the assumptions are false, in an area such as nuclear posture, in which the consequences of miscalculation and miscommunication are as catastrophic as misapprehension. On the other hand, significant new findings such as Narang’s may prove more beneficial for international security in the context of practitioners’ perspectives on best practices in promoting crisis stability, confidence, and effective negative control of nuclear weapons.

Additional research extending Narang’s theoretical approach to states that have not yet acquired nuclear weapons could reveal further insights. For example, Narang describes Japan as a “standby nuclear state,” raising the question of why this is not another possible value of his “nuclear posture” variable. Could the threat of future proliferation be sufficient to catalyze greater resolve in a patron to defend a near-nuclear state? Tristan Volpe, a Ph.D. candidate at The George Washington University, observes that states with the latent capacity to produce nuclear weapons often wait in a restrained yet costly preweapon stage of “nuclear limbo” to reap coercive bargaining advantages against friends and enemies alike.[2] Arrangements for nuclear sharing within an alliance, reliance on a nuclear umbrella without seeking an independent nuclear weapons capability, or membership in nuclear-weapon-free-zone agreements might widen the potential variation of “nuclear posture” further.

If Narang’s theory or some adaptation of it also drives the defense posture decisions of countries that are nuclear Nonproliferation Treaty (NPT) non-nuclear-weapon states, it could illuminate nonproliferation behavior within NATO and by other close U.S. allies. This would be of great interest to policymakers and might enable improvements in extended deterrence policy for nuclear nonproliferation. Specifically, if a superpower guarantor is always preferred to an independent nuclear weapons capability, what should the United States do to manage the risk of proliferation?

Variation of the “resource constraint” variable should be explored further. Narang indicates that it is relative to a prospective adversary. For example, it is low in India’s case because “anything Pakistan can afford, India can surely also afford.” This is an insufficiently clear criterion for reliably observing variation in resource constraint for three reasons. First, states sometimes assign a very high priority to nuclear weapons capabilities, as in Pakistani Prime Minister Zulfikar Ali Bhutto’s 1965 pledge that Pakistan would “eat grass” to match an Indian nuclear capability. Similarly, Narang says, France was “forced to adopt an asymmetric escalation posture before it was fully capable of doing so.”

Second, multiple adversaries may be implicated in a state’s nuclear strategy. For example, China is relevant to the Indian case, but with greater resources than Pakistan. That fact could alter the way that resources affect Indian posture choices.

Third, when Narang observes that resource constraint makes a state cautious to avoid an arms race that “could bankrupt the state or render it vulnerable,” it seems that a security dilemma, in which actions by one state to increase its security decrease the security of others, may be doing more work to explain that state’s restraint than budget pressure. Variation in resource constraint is already suppressed in Narang’s study by including only states that possess nuclear weapons, which Narang observes are not cheap. If resource constraint does not prevent proliferation, why should one expect it to prevent aggressive postures rather than, for example, allowing these postures with subpar negative controls against unauthorized use? Narang does not demonstrate the existence of states rich enough to build a bomb but too poor to choose a strategy for its employment. Instead, he finds that “the asymmetric escalation nuclear posture is both the curse of the severely threatened and the luxury of the rich and stable,” as France was forced to adopt this posture to face a vastly superior Soviet Union but free to retain it after the Soviet collapse because its domestic civil-military relations support a delegative command structure.

Narang repeatedly notes the inherent risk of the asymmetric escalation posture, but his theory seems to explain a world in which policymakers do not consider this risk in selecting a posture, which seems dangerous.

Political constraint imposed by other states seems to matter to Narang’s narrative explanations, but it is not included in his theory. Narang’s posture optimization theory and alternative explanations for sources of nuclear posture do not include references to political pressure by other states, but he refers to such pressure repeatedly to explain posture decisions. For example, India somehow sidestepped the first node in the decision tree of the posture optimization theory because relying on a superpower patron “risked undermining India’s position in the nonaligned movement.” In turn, “[f]ear of international backlash prevented [Pakistan] from fully operationalizing an asymmetric escalation posture by testing nuclear weapons” until India “midwifed” this change with its own testing in 1998. Further qualitative research to explore the role of political constraint could help to refine Narang’s theory in testable ways.

Narang claims that Chinese and South African policy choices were influenced by consideration of political costs while this mechanism remains unacknowledged in his theory. Moreover, he seems to cast the NPT as a global background condition affecting all states equally, robbing it of potential explanatory power. Political science has not yet explained the small number of states that have acquired nuclear weapons, and in this vacuum of scholarly explanation, it is imprudent to disregard the insight of many practitioners that the NPT is an important factor in preventing proliferation.

Additional research could clarify the role of perception in Narang’s theories. He provides a useful primer on theoretical perspectives, but treats deterrence at a length too great never to mention that it takes place in the mind of the adversary. The main reason that the requirements of nuclear deterrence are unknown is that they vary with the adversary to be deterred. His theory relies on objective facts to predict posture, but some of these facts, such as resource constraint and the availability of a more powerful patron, are subject to the perceptions of decision-makers.

The book has numerous additional policy implications that should be explored. Can U.S. policy choices encourage a posture change back from asymmetric escalation to assured retaliation, catalytic, or any latent nuclear posture? How should the United States respond to the nuclear postures of additional states that newly acquire nuclear weapons? How will those states respond in turn? Could widening multilateral participation in direct communication links and nuclear risk reduction enhance crisis stability? Perhaps most importantly, would an asymmetric escalation posture deliver additional national security benefits to a state such as India against conventional or terrorist attack? If so, this finding would be very important and potentially dangerous if it supported policy arguments for more-aggressive nuclear postures. Such findings should be explored, but also combined with input from nuclear policy and military practitioners whose backgrounds may have exposed them to practical dangers of nuclear first use that are difficult to capture in a study with no data on inadvertency.

Narang adds importantly to the scholarly understanding of nuclear posture in a way that can inform policy. He studies an important topic, shatters false assumptions, provides insightful and useful new conceptual categories, offers apparently powerful theoretical explanations of important behaviors, provides a valuable set of case studies, and opens doors for additional scholarly research. At the same time, Narang’s findings should be scrutinized carefully and his policy advice assessed from additional perspectives before it is used to justify changes in nuclear posture. The many avenues for additional research it suggests and worrisome possibilities it surfaces testify to the analytic strength and policy ambition of this important book.

Douglas B. Shaw is associate dean for planning, research, and external relations at The George Washington University’s Elliott School of International Affairs, where he also is an assistant professor of international affairs. During the Clinton administration, he served in the U.S. Arms Control and Disarmament Agency and the Department of Energy. He holds a Ph.D. in international relations from Georgetown University


1. Stephen M. Meyer, The Dynamics of Nuclear Proliferation (Chicago: University of Chicago Press, 1986).

2. Tristan Volpe, “Proliferation Blackmail: The Coercive Threat Advantages of Nuclear Latency” (Ph.D. dissertation, The George Washington University, forthcoming).