Many scholars and policymakers are concerned that the emergence of drone warfare—a first step toward the robotics age—will promote instability and conflict at the international level. This view depends on the widely shared assumption among International Relations scholars that military hardware spreads easily, especially in the age of globalization and real-time communications. In this article, we question this consensus. Drawing from the literature in management, we advance a new theory of diffusion of military innovations and test its two underlying causal mechanisms. First, we argue that designing, developing, and manufacturing advanced weapon systems require laboratories, and testing and production facilities, as well as know-how and experience that cannot be easily borrowed from other fields. Second, we argue that the adoption of military innovations requires both organizational and infrastructural support. We test our two claims on three types of combat-effective drones: loitering attack munitions (LAMs), intelligence surveillance and reconnaissance drones (ISR), and unmanned combat autonomous vehicles (UCAVs). We find that even wealthy, advanced, and militarily capable countries such as the United States, the United Kingdom, Germany, and France have struggled to produce or adopt such platforms. We conclude that concerns about the diffusion of drone warfare appear significantly exaggerated, as do claims that globalization redistributes military power at the global level. More generally, our analysis sheds light on how the interaction between platform and adoption challenges affects the rate and speed of diffusion of different military innovations.