Pivotal deterrence highlights the problem of dual deterrence in which one state (pivot) attempts to preserve the status quo and prevent conflict between two revisionist adversaries, while each depends on the pivot's support and/or neutrality for its ultimate success. Timothy Crawford's book is an important and, in several ways, original statement on a topic unduly ignored in past studies. In the first two chapters, the author carefully lays out his theoretical expectations concerning the conditions that make pivotal deterrence 1) possible, 2) probable, and 3) likely to succeed. A set of necessary conditions expected to make pivotal deterrence possible are clearly outlined: The two adversaries must see each other as more threatening than the pivot, whereas the pivot must be at least equal in power to them, prefer the status quo between them, and believe that both adversaries are revisionist and willing to go to war if assured of its support.

The author then tackles the next issue of what makes pivotal deterrence attempts probable. Here, Crawford provides an interesting angle and novel use of an old problem concerning the interplay between the balance of power and interests. Depending on whether the pivot's interests in the adversaries are vital or secondary and its power preponderant or equal to them, there are four possible combinations, though only two are expected to give rise to pivotal deterrence. The author perceptively resorts to the logic of selection bias to rule out the situation of a pivot's equal power and secondary interests as unlikely to trigger such attempts, because the pivot should reasonably anticipate almost a sure failure and, thus, unlikely select itself into the crisis. Similarly, the reverse situation of a pivot's vital interests and preponderant power predisposes it to success, which, in turn, should make general deterrence work. We are then left with two conditions that are likely to trigger attempts at immediate pivotal deterrence—the pivot's equal power/vital interests or its preponderant power/secondary interests. The cases are selected to represent each of these two contingencies, as both are necessary for attempts to occur, but neither is sufficient to determine their eventual success or failure.

The book's main concern is with the outcomes of pivotal deterrence, which are principally attributed to varying alignment options available to adversaries. Crawford rests his compelling explanation on the premise that the pivot's bargaining leverage declines or strengthens in proportion to the number of alternative “pivotal” allies (if any). Moreover, there is a detailed analysis of specific causal mechanisms leading to success or failure under varying alignment options. Overall, minimal (“scarce”) alignment options should lead to success in preventing war, but need also be accompanied by the “uncertainty effect” by which the pivot keeps the adversaries unclear about its ultimate allegiance in case of failure. If uncertain about the pivot's commitments, both adversaries would exercise caution and/or compromise to avoid alienating the pivot. On the other hand, alternative (“abundant”) alignment options work against success by creating avenues through which the pivot's bargaining leverage is undercut. The careful discussion of several peace- and failure-inducing mechanisms presents one of the most interesting points in the book.

The case selections are guided by a concise and excellent treatment of relevant methodological points, and the empirical analysis is expertly done. Crawford shows a mastery of the methods of causal analysis in historical case studies, making this a primer in qualitative research design. The tests show that the pivot succeeds if the adversaries cannot substitute their dependence on its support with alternative alignment options, as analyzed in the cases of Bismarck's attempts to preserve the status quo between Austria-Hungary and Russia in the Eastern Crisis 1875–78 (Chap. 3) and U.S. efforts to prevent war between Greece and Turkey in the Cyprus Crises of 1964 and 1967 (Chap. 5). The study insightfully dissects alternating Greek and Turkish approaches to Moscow in their intent to force the United States to compete with Moscow, and how America's consistent pursuit of pivotal deterrence policy minimized the destabilizing effects of such attempts at alignment diversification. Although each case presented different variants of the pivot's interests and power (vital/equal in the former case and secondary/preponderant in the latter), the absence of effective alternative alignment options directed adversaries toward restraint.

I was a bit intrigued by the 1870s Eastern Crisis analysis that places Germany as the pivot deterring Austria and Russia. A more conventional approach attributes the eventual Russian concessions to Britain's overt threats as a protector of its interests in Turkey. That is, the same episode can alternatively be interpreted with Britain as the key deterrent figure and, perhaps more important, as a classic form of extended immediate, rather than pivotal, deterrence. The crisis was too complex, however, to sustain only one analytical angle, and the author made a valid case for seeing it through pivotal deterrence lenses as well.

Conversely, alternative alignment options led to pivotal deterrence failure in both critical combinations of the pivot's interests and power. The British failed to preserve the status quo and deter France and Germany from escalating in the 1914 July Crisis (Chap. 4), and U.S. efforts proved unsuccessful in preventing war between India and Pakistan in the Kashmir Conflict of 1962–65 (Chap. 6). The examination of South Asian crises is particularly successful, showing how the Sino-Indian conflict drew China to Pakistan, which then predictably drove India closer to Moscow, all of which hampered U.S. bargaining leverage as a pivot. As for the 1914 July Crisis, given the differences between many schools of thought that are far from being resolved, it is only fair to say that Crawford's is yet another interesting take, perhaps more informative for international relations theory than World War I historiography, on this perennial historical controversy.

The book concludes with a discussion of how the theory sheds light on the recent U.S. successes and failures in preventing wars among third parties. For example, the analysis of the Kosovo crisis was refreshing for its strictly strategic context, and is one of the most penetrating studies of this crisis from a strategic vantage point.

There could have been a more thorough examination of deterrence theory, however, recognizing several distinct approaches. Identifying the entire corpus of deterrence theory with the premise that “the best way to achieve deterrence is to make your threats and promises early, clearly, and publicly” (p. 12) is obviously too narrow. There is a long-standing argument advocating strategic unclarity in many forms of deterrence, but the author seems to identify it primarily with pivotal deterrence.

Relatedly, the book takes a somewhat restrictive conceptual understanding of extended deterrence, juxtaposing it to pivotal deterrence. One could argue, however, that some scenarios of pivotal deterrence can be interpreted as modified extended immediate deterrence (EID). This is most notable under the “straddle strategy” scenario in which the pivot (i.e., defender in EID) believes that one side would not go to war without its support, while the other would if the pivot stays neutral. It is not surprising, then, that some of the cases identified with pivotal deterrence have been analyzed elsewhere as extended immediate deterrence (e.g., 1914 July Crisis or the U.S.-Taiwan-China triangle). Had the author recognized the much closer affinity between these two forms of deterrence, he could have acknowledged his possible contributions to extended deterrence research as well. This is particularly true for its potential toward solving the complexities of the moral-hazard problem between defender and protégé, an issue inexplicably neglected by many analysts.

That said, Pivotal Deterrence is a fascinating read, profuse with engaging arguments, sure-handed historical research and elegant narratives, and ingenuities in drawing policy implications for current U.S. foreign policy. Crawford makes an important contribution to diverse areas of conflict research, including deterrence, alignments, defensive realism, mediation as coercive diplomacy, and overall war prevention. His book should undoubtedly have strong appeal for both international relations scholars and policy practitioners.