Among the potentially most consequential effects of populism is its impact on countries' international conflict behaviour. However, empirical evidence about populists' approach to international disputes is inconclusive. We develop a theoretical framework focused on mobilization and personalization, which we argue are particularly relevant characteristics of populist foreign policy-making. We hypothesize that, on a conflict–cooperation continuum, a country's approach to a bilateral dispute will become more conflictive under a populist government if that dispute is strongly used for domestic political mobilization, and if decision-making on that issue is highly personalized. Conversely, foreign policy will not become more conflictive in cases of weak mobilization and personalization. We carry out in-depth qualitative within-case comparisons of non-populist and populist governments' policies in Bolivia (2002–2019), India (2004–2022), and the Philippines (2010–2022), focusing on two selected bilateral disputes per country. Drawing on a broad range of sources, including 71 expert interviews conducted in the three countries, we find that populists in power escalate international disputes if they strongly use foreign policy issues for domestic mobilization and, at the same time, strongly personalize decision-making. This finding nuances existing assessments about the effect of populism on foreign policy change.
