Peace at Home, Conflict Abroad: Government Ideology, Mission Type, and Parliamentary Support for Military Interventions

International relations scholarship has long overlooked the role of parliament in shaping states’ decision to go to war. In contrast, recent studies explored variations in parliamentary war powers across time and countries and their impact on troop deployments abroad. However, a systematic analysis of the determinants of support for military interventions in parliament is still missing. This article fills this literature gap by examining votes on 119 missions in twenty-one democracies between 1990 and 2019. Our findings suggest that parliamentary contestation is fundamentally driven by government ideology and the type of mission. Parliamentary support for military intervention is significantly higher when a left-wing government is in power. Moreover, “inclusive” missions with a robust humanitarian dimension draw a considerably lower level of contestation than “strategic” missions aimed at contrasting a security threat. Through such findings, the article contributes to the debates on the relevance of domestic political institutions in foreign policy and the party politics of military interventions.