Bounded altruism: INGOs’ opportunities and constraints during humanitarian crises and the US intervention in Bosnia-Herzegovina and Kosovo

International humanitarian nongovernmental organisations (NGOs) and government donors have grown increasingly close in the past two decades as they responded to conflict and post-conflict situations, with effects on each other that remain unclear. We advance a dynamic understanding of the opportunities and constraints that international NGOs (INGOs) experience in their relationship with the US government in conflict zones, arguing that shifts in INGOs’ potential to influence US responses are situationally determined. We offer three explanatory variables (aid market structure, bureaucratic regulatory environment, and US government demand for INGO services) to explain when and why INGOs possess opportunities for autonomy, and when their actions are constrained by donors. Applying this framework to the conflicts in Bosnia-Herzegovina and Kosovo, we conclude that INGOs possess the greatest opportunities during violence-induced humanitarian crises and experience many more constraints during peacekeeping scenarios.