The end of the cold war has heightened the importance of burden-sharing within ad hoc collective security coalitions. Operation Desert Storm represents an important case of such a coalition. Although a large literature examines the disparate size of allied states' collective action problems in regard to their alliance contributions, little effort has been made to assess other explanations for contributions. This article evaluates that hypothesis and four additional hypotheses that help to explain not only the amount but also the kind and timing of the burdens borne by members of the Desert Storm coalition: two external hypotheses-balance of threat and alliance dependence-and two internal hypotheses-state autonomy and domestic politics plus bureaucratic politics. Structured, focused case studies of policy processes in Britain, Egypt, France, Germany, Japan, and the United States are used to evaluate the hypotheses. We find that external pressures, especially alliance dependence, explain political leaders' incentives to contribute to alliances, while internal constraints account better for their ability to contribute and for the form those contributions take. Our integrated model accounts for four polar types of contribution outcomes, with an emphasis on the importance of alliance dependence in producing them.
