When do militaries in the newly industrialized countries of East and Southeast Asia support their governments, when do they support citizens' challenge of government, and when do they launch coups? We propose and test a theory of military behavior using data from across East and Southeast Asia between the 1970s and 2008. The results corroborate the model's predictions to make four contributions: First, the model provides a framework of military behavior for countries to expand study beyond coups or the absence thereof. Second, the findings bring to focus the influence of citizens on the military's behavior, an aspect largely overlooked in scholarship of the region. Third, the necessary conditions-weak economy and galvanized citizens' challenge- that affect the military's behavior vis-à-vis citizens and the government highlight the strategic interaction treatment. Fourth, this study broadens systematic treatment to enrich empirics and theory-building for the political economies of these countries.