External Threats and Support for International Security Cooperation

Abstract

Are voters more supportive of external security commitments when international threats increase? While international relations scholarship treats threats as key drivers of state behavior, less is known about threat perception and the micro-foundations of public support for security cooperation. Because international security commitments entail both costs and benefits, threats may not uniformly increase support for cooperation, complicating analysis. We examine this question through pre-registered survey experiments in Japan and South Korea that vary information about external threats by source and intensity. Comparing geographically proximate Japan with more distant South Korea allows us to assess how exposure to regional insecurity shapes public attitudes. We find that information about a possible Chinese invasion of Taiwan significantly increases support for international security cooperation in both countries. However, this effect depends partly on the proposed partner state, suggesting that threat-induced support for cooperation is conditional rather than uniform.