The Spread of Military Innovations: Adoption Capacity Theory, Tactical Incentives, and the Case of Suicide Terrorism

What explains the adoption of military innovations? In this article, we assess the empirical validity of adoption capacity theory by reconsidering one methodologically important case analyzed by Michael Horowitz: the diffusion of suicide terrorism. We show that, when addressing problems in Horowitz's research design, the case of suicide terrorism fails to support adoption capacity theory. We argue that, in order to account for the diffusion of this innovation, one needs to take into consideration the tactical incentives to overcome technologically superior enemies. The results of our quantitative and qualitative analyses suggest that terrorist groups fighting against very powerful states in terms of conventional capabilities are more likely to employ suicide attacks than those fighting against poorly equipped ones. Our findings are important because they provide systematic evidence in support of Kalyvas and Sànchez-Cuenca's argument that suicide terrorism is driven by tactical considerations and because they provide confidence in the external validity of Berman and Laitin's hardness of targets hypothesis. Our results also question Lyall and Wilson's finding that highly mechanized armies are inherently inadequate to win counterinsurgency operations. The superior conventional capabilities of a counterinsurgency army might in fact make traditional insurgent tactics ineffective and thus give insurgents an incentive to adopt suicide attacks.