Although international crises are often believed to represent windows of opportunity to strengthen European defense cooperation, recent crises have not seemed to produce a clear convergence of European Union (EU) member states' security interests. This article seeks to address this puzzle by arguing that European defense cooperation is a response to crises that place European states in a situation of military interdependence. Conversely, asymmetric crises, i.e. crises that affect European states unevenly, encourage those states to maintain their autonomy of action. This theoretical argument is supported by two case studies: the failure of the European Defense Community in the early 1950s and the current difficulties experienced by the EU's military operations. These two cases illustrate a striking continuity in that, because of (neo)colonial ties in particular, European states are often unevenly affected by international crises, which tends to make defense cooperation less effective. On the other hand, the recent wave of terror attacks in Europe and the prospect of Brexit negotiations have renewed the impetus to hold talks regarding the possible strengthening of European defense cooperation (Gentiloni and Pinotti 2016, Le Figaro 2016). In light of these hopes and disappointments, identifying the key factors through which crises can (or cannot) stimulate European defense cooperation is crucial. Without denying the importance of the American factor, this article aims to reopen the debate based on two observations. On the one hand, with regard to the EDC, the US commitment to maintaining a strong presence on the European continent dates back to September 1950. This factor alone does not explain why France supported an ambitious European army project in October 1950 and changed its mind only after much hesitation in 1954. On the other hand, the CSDP might have been initially established to take over for NATO in the Balkans, in a context marked by a relative US disengagement from Europe in the 1990s.However, since the CSDP has become operational, the vast majority of EU military interventions have been deployed to Africa, which had never previously been a favored destination for NATO interventions. In Africa, the CSDP essentially took over for former colonial powers' national policies rather than for NATO. Therefore, in Africa, the key question is not so much why Europeans started to act without the US but why they started to act together.Pierre Haroche 3 US policy alone cannot explain why joint EU operations became a regular practice in Africa in the early 2000s and then proved increasingly difficult to launch a few years later (Haine 2011, Koepf 2012. European defense cooperation can only be understood by adopting a more comprehensive analytical framework.Theoretically, this article aims to demonstrate that European defense cooperation is a response to the military interdependence that international crises impose on European states. In particular, this article investigates the impact of crises on Europea...