Allies and diffusion of state military cybercapacity

Understanding the diffusion of military capabilities is a central issue in international relations. Despite this, only a few works attempt to explain this phenomenon, focusing on threats. This article explains why threats alone cannot account for cybercapacity-development diffusion and introduces a more consistent explanation: the role of alliances. Allies with cybercapacity help partner-countries without cybercapacity start developing their own capacity to increase the alliance’s overall security by reducing mutual vulnerabilities in cyberspace. Partner-countries that lack cybercapacity are eager to accept this option because it is more favorable than developing cybercapacity on their own. Partner-countries may also start investing in cybersecurity to reduce the likelihood of being abandoned in other, conventional, domains. My new cross-sectional time-series dataset on indicators of a state’s cybercapacity-development initiation for 2000–18 provides robust empirical support for this argument and offers important implications for scholarship on arms, allies, and diffusion.