Leader Similarity and International Sanctions

It is well-established that political leaders matter for domestic outcomes, but statistical evidence for their relevance in international politics is comparatively scarce. We ask whether the personal relationship between political leaders can change the propensity for nonviolent conflict between nation-states in the form of sanctions. Panel probit models with data from 1970 to 2004 are estimated to evaluate whether more similar leaders are less likely to sanction each other. Our results indicate that higher leader similarity reduces the likelihood of sanction imposition. The effect is most pronounced for sanctions imposed through unilateral political decisions. The probability of such sanctions ranges from 2.3 percent at the highest observed leader similarity to 7.2 percent at the lowest. Leader similarity especially matters for sanctions aimed at democratic change or human rights, for non-trade sanctions, and when at least one autocracy is involved. Finally, leader similarity has become more important after the Cold War.