Donald Trump’s remarks concerning the North Atlantic Treaty Organization (NATO) and its obsolescence during the 2016 American presidential campaign may have thrust the alliance into the popular spotlight, but the need for a more extensive and nuanced understanding of the organization has been a crucial weakness in international relations scholarship for decades. Seth Johnston’s How NATO Adapts untangles the puzzle of one of the most long-standing, well-institutionalized military alliances in the contemporary era. Supporting an institutionalist approach with extensive historical analysis and process tracing, Johnston provides compelling evidence to demonstrate the alliance’s ability to adapt, exercise power and autonomy, and define and execute its objectives independent of the member-states comprising it.

Johnston’s integration of historical institutionalism and critical juncture theory leads to two central claims: that NATO is an autonomous institution, and that its institutionalization allows the alliance to maintain the ability to dictate (to some degree) its future. He rightly asserts that the weakness of existing NATO studies is their state-centric structural approaches. Especially in light of NATO’s “latest organizational and strategic behavior,” Johnston argues the necessity of a modified framework in order to “identify continuities in the context of historical challenges to NATO’s institutional endurance” (p. 4). An institutionalist approach allows for identifying the alliance’s functions as a prototypical bureaucracy and demonstrating the power derived from institutionalization, while also distinguishing its unique characteristics from other international organizations. The application of critical juncture theory creates a mechanism for explaining how the alliance adapts, as well as a more nuanced understanding of the structural, institutional, and individual actors facilitating this adaptation.

In one of the theoretical contributions of the book, Johnston employs process tracing to construct a narrative of the oft-overlooked institutional changes to the alliance. His selection of three time periods, 1950–55, 1962–67, and 1992–97, allows for a concise analysis of several critical junctures in NATO’s evolution, including the Korean War, the Second Berlin Crisis and Cuban Missile Crisis, and the end of the Cold War. The selection of these cases “shows significant variation in the substance of the crises facing NATO, allowing for multiple applications of the congruence method,” even after controlling for antecedent conditions (p. 5). The mechanisms through which individual actors pursued adaptation, conceptualized in Chapter 3—convening, agenda-setting, delegating, information-sharing, delaying, moderating, and coopting (pp. 28–31)—are clearly identified in each case, enhancing the author’s claims of organization independence from state influence. Within each case study, he also identifies the moment in which alternatives to NATO adaptation surfaced. In many instances, especially in the post–Cold War era, these alternatives share a common characteristic: divorcing the security of Europe from reliance on the United States.

Johnston’s analysis propels NATO studies in a promising new direction, far from the state-centric analyses dominating the early decades of the alliance. The book also raises significant questions about where to go next. Notably, the author argues in support of understanding the alliance independent of its member-states, but asserts the need to recognize how NATO does not function in a vacuum. One solution to this would be to expand the framework to include mechanisms designed to identify when, why, and how the interests of states prevail over whatever institutional power that actors hold. Integration of Johnston’s system-level analysis with a state-level analysis would allow for a more robust explanation for the persistence of the alliance, in addition to its institutional development and resulting power.

A hybrid analytical framework would result in several benefits, especially in regard to the contemporary challenges facing the alliance. In each of his case studies, Johnston acknowledges the unique role played by many American actors. In his first case regarding the question of West Germany and the Korean War, for example, Johnston details the importance of American officials in particular. Dwight Eisenhower’s reputation in establishing the position of Supreme Allied Commander Europe (SACEUR) while also serving as the commander of U.S.European forces, for example, constituted what Johnston labels “dual-hatting.” He writes “This dual-hatting allowed these actors to blend powers or invoke the special credibility, prestige, and power of the United States in the service of their NATO-specific institutional duties” (p. 79).

The author also explores how the U.S.—NATO dynamic was again challenged after the conflict in Kosovo and the war in Afghanistan. Defense Secretary Donald Rumsfeld was particularly instrumental in the “marginalization” of the alliance after the 9/11 attack, notes Johnston, after U.S. Ambassador Nicholas Burns and National Security Advisor Condoleezza Rice deemed American involvement in the invocation of Article V unnecessary (p. 166). Despite presenting considerable evidence illustrating the advantages of being a U.S. official versus an official from another member-state, Johnston argues that the North Atlantic Council’s consensus rule mitigates power imbalances between the member-states themselves. Power imbalances do exist and do affect institutional adaptation, but are treated as a consequence of the specific actor, not the member-state from which he or she originates.

It is hard to ignore the influence of the United States and its representatives over some, if not all, of the alliance’s day-to-day functions, however. Nearly three-quarters of NATO’s defense expenditures are paid by the United States, while the SACEUR has been an American officer by tradition since Eisenhower’s appointment in 1950. The only invocation of the North Atlantic Treaty’s collective defense provision Article V occurred in the wake of the 9/11 tragedy. The desire to shape the alliance to its interests is arguably a powerful motivator of state behavior toward and within the alliance. Many states, including the United States, regularly use institutions like NATO to launder policy initiatives, thus making their decision making more palatable to domestic constituencies. (e.g., see Kenneth Abbott and Duncan Snidal, “Why States Act Through Formal International Organizations,” Journal of Conflict Resolution, 42(1), 1998). A failure to do so can backfire, as evidenced by the 2003 Iraq War. Patricia Weitsman and Sarah Kreps, among others, demonstrate the military, economic, and political consequences of U.S. actions through ad hoc coalitions or unilateralism in lieu of NATO support (Patricia Weitsman, Waging War, 2014; Sarah Kreps, Coalitions of Convenience, 2011). Finally, state-level research demonstrates how member-states have shaped their actions with regard not to the alliance but, rather, to their relationship with the United States (e.g., see Jason Davidson, America’s Allies and War, 2011). All of this raises the question: Does American influence not permeate the strategic and long-term planning of the organization? And if so, does this not significantly diminish the power of institutional actors?

This does not, however, diminish the contributions of the book to the study of alliances. Johnston rightly identifies the biases in previous analyses of NATO, including the treatment of member-state interests and alliance interests as parallel, if not synonymous. Instead, the identification of NATO’s institutional adaption and autonomy allows for future analysis of the power dynamics between member-states within the alliance and a clearer understanding of particular outcomes. Further, if one accepts Johnston’s claims regarding adaptation as a function of power politics (p. 23), there must be some consideration of the dynamics between state actors and institutional actors. In fact, reliance on institutions like NATO as a resource in the U.S. foreign policy toolbox for capacity enhancement or political cover cedes power to the alliance. Applying broader international organization theories while simultaneously recognizing the unique characteristics of NATO is imperative if progress is to be made in understanding the adaptation and persistence of the alliance. How NATO Adapts is a tremendous step in that direction, as it allows for deeper understanding of the institutionalization of NATO from the organization’s perspective.