Rachel Elizabeth Whitlark’s ambitious and thought-provoking book, All Options on the Table: Leaders, Preventive War, and Nuclear Proliferation, asks why some leaders, but not others, choose to conduct preventive strikes against adversaries’ nuclear weapons programs. Whitlark situates her investigation in a timely and active debate: In the international system, do states act in accordance with realist assumptions, or do individual leaders’ beliefs affect foreign-policy decision making? Renewed interest in this question has arisen not only within the international relations literature but also within general audiences seeking to understand significant foreign policy shifts from one US presidential administration to the next.

Whitlark enters this debate by examining preventive military action in the context of nuclear proliferation. She theorizes that leaders, guided by their individual beliefs, determine whether the nuclear-aspiring adversary may pose a significant enough threat in the future to warrant preventive action. A leader is most likely to use preventive military force to slow or stop a nuclear weapons program if three conditions hold: First, if the leader believes that nuclear proliferation is destabilizing, second, if the leader believes that the proliferating adversary will pose a threat upon becoming a nuclear weapons state, and third, if the leader is then advised that force is likely to succeed.

The last element of this decision calculus (likelihood of success) is operational, and is thus different from the first two elements, which concern leaders’ prior beliefs. Beliefs about the nature of proliferation, and the adversary’s intentions and resolve, shape how a leader interprets proliferation behavior and whether that leader ever considers the option of preventive force in the first place. Whitlark looks for evidence of these beliefs in a leader’s writings and statements prior to taking high office and, in most cases, in the early months or years of the leader’s tenure as well. Sometimes, Whitlark weaves multiple sources together to offer a compelling picture of a leader’s prepresidential nuclear proliferation views; in other cases, a dearth of available information leaves Whitlark with less to go on. As she rightly tells the reader, an absence of evidence does not equate to evidence of absence. One must proceed with caution.

The research design is particularly strong. To test her arguments, Whitlark examines cases in which at least two different leaders—in most cases, US presidents—faced potential threats from the same adversary. By holding the pair of states constant within each study, Whitlark can more confidently point to consecutive presidents’ different individual beliefs to explain their different preferences for preventive war. This comparative approach is smart and well executed, but nonetheless has some shortcomings. For instance, when an international crisis arises only in the later presidency, as is the case with North Korea in the comparative study of the George H. W. Bush and Bill Clinton administrations, the waters become muddied. Determining whether Clinton’s interest in preventive action is influenced more by his prior beliefs or by North Korean escalation becomes particularly challenging. Despite such difficulties, the design still allows Whitlark to establish a context for each study that comes as close as possible to holding key variables constant across the selected administrations.

All but one of the cases in the book concern presidential decision making in the United States. The final case chapter, which aims to test the theory beyond the United States, concerns three Israeli prime ministers: Yitzhak Rabin, Menachem Begin, and Ehud Olmert. However, the lack of existing information means that Whitlark can only offer conjecture regarding the relationship between each Israeli leader’s beliefs and preventive war decision making. This points the way to future research should documents become available. Indeed, choosing to focus the study on the United States is sensible. The United States has been one of the most frequent interveners in foreign nuclear weapons development. Moreover, studying decision making within a single country allows Whitlark to make more granular claims across administrations and foreign policy eras.

This granularity, which emerges directly from the rich array of evidence used to examine presidents’ beliefs, is another major strength of the book. At times, Whitlark’s use of documents from the archives of multiple presidential libraries, among other sources, directly reveals a president’s beliefs about the dangers of nuclear proliferation. In chapter 3, Whitlark’s careful assessment of John F. Kennedy’s fears regarding nuclear proliferation, including the risk of accidental launch, contains fascinating material from Kennedy’s diary. In an entry from summer 1945, Kennedy references, with horror, a new weapon that we can clearly understand to be the atomic bomb. Kennedy should not have known about the Manhattan Project (he likely learned of it through his political connections). The United States had not yet attacked Japan with nuclear weapons, yet Kennedy already feared the bomb’s terrible power. This kind of archival evidence brings the case studies to life, and tells us more about leaders’ beliefs than the typical hawk/dove categories can.

Rather than limiting the study only to the consideration of preventive action against nuclear weapons programs during peacetime, Whitlark also examines leader beliefs and preventive strikes during the wider US military operations in Iraq. In this case, preventive strikes against suspected weapons of mass destruction facilities were conducted either within a war (Bush 41 and Bush 43) or in the midst of ongoing no-fly zone enforcement and other military operations (Clinton). For each of the three presidents, Whitlark marshals evidence that convincingly supports linkages between beliefs and action. In particular, she demonstrates Clinton’s direct interest in preventive force through multiple sources, including Clinton’s conversations with foreign leaders. Interestingly, the most persuasive evidence concerning Bush 41 involves his beliefs about Iraq and Saddam Hussein rather than his beliefs about nuclear proliferation. Which of the two types of beliefs—beliefs about proliferation or beliefs about the adversary—matters more? Readers will decide for themselves which way the scales may tip for each leader and case.

How far can leader beliefs take us in understanding actions taken against aspiring nuclear weapons states? Would we expect beliefs about nuclear proliferation to affect the likelihood that a president engages in costly diplomatic efforts aimed to slow an adversary’s progress toward nuclear weapons, or initiates significant arms control measures? While I am convinced by the evidence that Bush 41, for instance, held to a strategy of diplomatic engagement and did not consider preventive action against the North Korean program, I find it difficult to reconcile the argument that he may have held optimistic beliefs about proliferation with his sweeping presidential initiatives regarding nuclear arms. This book, in successfully challenging the logic that security concerns explain preventive war, will lead readers to consider many different ways in which the framework of leader beliefs could be applied to nonproliferation policy making at the highest levels of government.

By demonstrating the value of studying leaders’ beliefs, Whitlark successfully challenges the baseline assumption that security explains nuclear weapons decision making. This book makes an important contribution to our understanding of both the role of leader beliefs and the domestic sources of support for the use of preventive force, and will interest a broad set of audiences.