Citizen distrust towards the rival country is a defining feature of protracted international rivalries, undermining meaningful cooperation that can lead to mutual benefits. How might governments establish a public opinion base that is more supportive of cooperation with the rival country? We argue that information about ongoing environmental cooperation with the rival country makes citizens more supportive of non-environmental cooperation by changing their beliefs about the rival’s trustworthiness and facilitating extrinsic reciprocity. We investigate this potential micro-level cooperation spillover in the context of the longstanding rivalry between Japan and South Korea. Our survey-based experiment finds that information about cooperation on marine plastic pollution shapes the public’s willingness to cooperate in terms of the economy and security. Importantly, however, we find asymmetric results in Japan and Korea. While Koreans are more receptive to our positive cooperation treatment, which increases their willingness to cooperate in other domains, Japanese respondents react more strongly to the negative non-cooperation treatment, which reduces their willingness to cooperate in other domains. We offer explanations for these divergent reactions based on prior interactions between the two countries. Our findings have important policy implications for conflict-ridden areas of the world beyond East Asia that increasingly face common environmental challenges.
This was originally published on SAGE Publications Ltd: Journal of Peace Research: Table of Contents.