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The Diffusion of Military Power: Causes and Consequences for International Politics

The Diffusion of Military Power: Causes and Consequences for International Politics by Michael C. Horowitz. Princeton University Press, 2010, 265 pp.

While innovation may not be replicated, innovation in the production, deployment, and application of military power is paramount in influencing global politics. However, “most assessments of the international security environment fail to incorporate either the relevance of military innovations or the importance of their spread,” according to author Michael Horowitz, who examines “the spread of military power throughout the international system, explaining how variations in the diffusion of new military innovations influence international politics, especially the balance of power and warfare” (p. x). He introduces his “adoption-capacity theory” in which he argues “that for any given innovation, the financial resources and organizational changes required for adoption govern the system-level distribution of responses and influence the choice of individual states” (ibid.). He also addresses “why some military innovations spread and influence international politics while other do not. . . . Adoption-capacity theory posits that for any given innovation, it is the interaction of the resource mobilization challenges and organizational changes required to adopt the new innovation, and the capacity of states to absorb these demands, that explain both the system-level distribution of responses and the choices of individual states” (ibid.).

In his opening chapter, Horowitz addresses the innovation of suicide bombing from the perspective of how financial and organizational constraints influence terrorist groups’ decisions. The high organizational change requirements for adoption explain why older, previously successful terrorist groups like the Provisional Irish Republican Army (PIRA) and the Basque Fatherland and Freedom Group (ETA) did not adopt suicide terrorism, while al-Qaeda did. He concludes that potential information age shifts in the production of military power could influence the future of the international security environment for both state and nonstate actors, including the United States, China, and al-Qaeda. Furthermore, “adoption-capacity theory combines research on the way both militaries and businesses change with new insights into the relative costs of new military systems to explain how military innovation spreads once it has been introduced into the international system” (p. 9). The theory disaffirms that “once states have the necessary exposure to an innovation, the diffusion of military power is mostly governed by two factors: the level of financial intensity required to adopt a military innovation, and the amount of organizational capital required to adopt an innovation” (ibid.). The adoption-capacity theory also demonstrates that “the levels of financial intensity and organizational capital required to adopt an innovation not only significantly influence the rate and extent of its spread throughout the international system but also drive its effect on international politics” (p. 11). Adoption-capacity theory may explain “the way different types of warfare in the future will provoke different type of reactions on the part of the responding actors, and the benefits or disadvantages different states” (p. 13). The theory also shows how the likely implications for the security environment depend on particular assumptions about the future.

Horowitz next defines what counts as a major military innovation and the theory of diffusion, concluding with a discussion of the cases selected for analysis: British naval innovations in the late nineteenth and early twentieth century, carrier warfare, and the advent of nuclear weapons and suicide bombing (p. 16). He cites the adoption-capacity theory as a “new approach to studying the introduction and spread of major military innovations . . . [which continues to be built on] existing research on military innovations and emulation to produce a framework for explaining the way that military innovations spread throughout the international system” (p. 64).

The author addresses the post–World War II gap between the diffusion of aircraft carrier technology and that of carrier warfare as an operational practice (p. 65). The high financial and organizational requirements for adoption cause most naval powers to evaluate the cost and benefits of their naval strategy differently than “they did in response to the naval innovations of the past, driving a larger proportion of states to drop out of the naval power game, bandwagon, or try to counter U.S. naval supremacy through alternative means” (p. 66). He notes that “countering the carrier, in the form of submarines and anti-ship missiles, has become a vastly more preferred strategy for most of the countries of the world than attempting to adopt carrier warfare or even acquiring fleet aircraft carriers” (p. 97).

Three essential arguments about the spread and impact of nuclear weapons are examined in chapter 4. “First, the exceptional nature of the potential destruction from nuclear weapons means even rudimentary nuclear weapons are still instruments of enormous power. . . . Secondly, the enormous level of financial intensity necessary to acquire nuclear weapons has always functioned as a significant constraint on the diffusion of nuclear weapons.” And finally, many states with the capacity to build nuclear weapons have chosen to bandwagon with the United States and pay alternative costs in the form of obligations within alliances rather than the high fiscal costs of weapon development” (p. 99). Adoption-capacity theory predicts that there should be changes over time in the ability of states to acquire nuclear weapons due to the diffusion of information and the growing number of scientists with nuclear experience, which will lower the financial intensity level required for adoption (p. 114). The theory also demonstrates that the high level of “financial intensity required for adoption drives the bigger nuclear picture in part. But the decreasing financial intensity required for adoption over time has opened the door to new adopters. Unlike with a battleship or aircraft carrier, a state can invest gradually over time in a nuclear program and the end result will still be highly relevant for international politics” (p. 133). As a financially intense innovation with low organizational barriers to entry, “nuclear weapons have traditionally widened the gap between the major powers and other states in the international system by setting up a global power litmus test” (ibid.).

Horowitz observes that it is possible to separate the key naval innovations of the late nineteenth and early twentieth centuries into two categories: the battlefleet innovation represented by the mighty dreadnought and the flotilla innovation symbolized by the torpedo boat and the submarine. The spread of the former occurred in line with the predictions of adoption-capacity theory. The huge difference between the pre-dreadnought and the dreadnought ships created a naval power gap that actually helped new naval powers like Germany gain on Great Britain after an initial period of inferiority, as they did not face the challenge of making over or abandoning an old and out-of-date fleet (pp. 164–65).

Similarly, Horowitz posits that it is possible to predict which groups are most likely to “adopt suicide terrorism not only by understanding religious networks but also through a better understanding of the organizational capital possessed by groups and the relationships between groups.” The adoption-capacity theory offers greater leverage than existing approaches in trying to determine why actors choose suicide terrorism and how this matters for international politics (p. 177). “The terrorist group has to decide that utilizing suicide terrorism will help accomplish its goals, requiring an evaluation of, among other things, the relative instrumental and/or symbolic benefits, the relative cost of training suicide bombers versus training for others types of terrorist operations and the potential repercussions in terms of reprisals” (p. 178). Also, more bureaucratized groups with multiple decision levels and veto points are likely to have more trouble shifting tactics to adopt. And since suicide terrorism by definition involves the death of members of the terrorist group and potential members with substantial expertise and knowledge, it cuts into organizational knowledge and expertise. Finally, there must be people not only willing to die for a specific cause but also willing to kill themselves for it. “The suicide terrorist does not want to die in the way an individual committing suicide does. Rather, the suicide terrorist has to die to accomplish a mission. This is a supply issue—finding people willing not simply to risk death but to kill themselves in pursuit of an organizational objective as well” (p. 205). Adoption-capacity theory helps explain the development and spread of suicide bombing, showing applications beyond major powers and even nation-states. Furthermore, the theory reveals how the high organizational capital requirements for adopting suicide terrorism made those terrorist groups that were most successful in the pre–suicide terror era unlikely to adopt the new innovation.

Horowitz also introduces the Kalyvas and Sanches-Cuenca theory, which is “not inconsistent with the adoption capacity theory. Adoption-capacity theory does not rule out that popular support could influence the interest of terrorist groups in adopting suicide terrorism, only that organizational constraints will prevent many groups from adopting and predispose others to adopt.” Further, while the two theories make “similar predictions for several groups, adoption-capacity theory more fully describes the decisions of more groups” (p. 206). The Kalyvas and Sanches-Cuenca contention is also limited by its “focus on terrorist groups as individual actors in a vacuum, rather than as linked actors in the international system. Adoption-capacity theory does not exclude the possibility that perceptions of success influence adoption” (p. 207).

Chapter 7 summarizes the previous chapters. The Diffusion of Military Power does not cover the entire universe of major military innovations, and the adoption-capacity theory does not address every factor that motivates state behavior. Nevertheless, the theory does advocate that “the consistent pattern of evidence across the cases suggests that failing to account for the diffusion of military power distorts the overall picture of international relations” (p. 209). The book attempts to explain issues ranging from the rate and scope of diffusion for particular military innovations to the circumstances in which shifts in relative power are most likely to occur and escalate to war. The concluding chapter explores the implications of adoption-capacity theory for international relations theory and applies it to debates in the United States and abroad regarding the future of warfare. One advantage of adoption-capacity theory is that it “can predict not only the behavior of greater powers but also that of smaller powers and nonstate actors” (ibid.). Adoption-capacity theory highlights the crucial distinction between when states attempt to respond to a major military innovation and whether or not that choice is likely to succeed. Furthermore, “military innovations are distinct from simpler changes because they are systems for applying military force, not just individual technologies” (p. 211). Adoption-capacity theory also helps “describe both why power transitions occur and how” (p. 212). It also “help[s] explain which types of actors are likely to benefit, which are likely to flounder, and the possible overall consequences for power balances and warfare, regardless of the specific vision for the future of warfare” (p. 216).

Finally, The Diffusion of Military Power illustrates the overall critical importance of understanding “how military innovations diffuse and affect international politics. Strategic competition, domestic politics, and international norms are all relevant factors influencing states to successfully adapt in different situations, however adoption-capacity theory provides a more complete picture of change in international politics, supplying a new answer to the puzzle of how military innovations influence the international security environment” (p. 225).

Albert H. Chavez, PhD, USN, retired

Embry Riddle Aeronautical University Worldwide

"The views expressed are those of the author(s) and do not reflect the official policy or position of the US government or the Department of Defense."

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