Abstract

Recent survey experiments have found that the public in NATO member states is more supportive of intervening militarily on behalf of formal allies than non-allies. However, we lack empirical evidence on whether this effect of alliance treaties generalizes to non-NATO and non-Western countries. To fill this gap, we conducted a preregistered cross-national survey experiment on population samples ( N = 7200) in two Western NATO countries (the United States and the United Kingdom) and four non-Western regional powers (Russia, China, India, and Brazil). The results of our experiment show that while allied commitments increase public support for military interventions globally, their effect is comparatively weaker in non-Western, non-NATO countries. Our findings contribute to the scholarly debates on the microfoundations of collective defense and the generalizability of IR experiments beyond the Western context.