Playing it safe: Audience costs, military capabilities, and alliance reliability during war

What kinds of states make the best allies? This dissertation studies the determinants of defensive alliance reliability during war. I argue that strong democratic states constitute reliable allies. For these states, the military costs of honoring an alliance agreement are sufficiently low, while potential electoral penalities are potentially large. For these reasons, strong democracies defend their allies during war more frequently. Support for this theory is found from a number of sources. First, I present the first individual-level experimental data supporting audience costs in the realm of military alliances. Second, I present observational data showing that strong democratic countries consistently defend their alliance partners during war.