--- - |2+ Objective With an aim of extending the scope of group threat theory from within‐country tensions between racial groups to international economic competition, this study specifically examined the impacts of perceived relative economic status of an in‐group country on attitudes about contentious political issues with a rival out‐group country. Methods Two survey experiments were administered, both of which manipulated Japanese participants’ perceptions of the relative economic powers of Japan and South Korea. Results When Japanese perceive that their country's economic power is declining relative to South Korea's economy, they demonstrate more hardline attitudes about territorial and historical issues between the two countries. Conclusion This study demonstrates the applicability of group threat theory to bilateral international relations. It also suggests that public opinion about international conflicts is a function of the long‐term rebalancing of economic power, which cannot be easily influenced by short‐term policies. - 'Social Science Quarterly, EarlyView. '