The United States has long urged greater contributions to regional security by its allies. Given the Obama administration’s shift in emphasis to Asia it is reasonable for the United States to urge the EU to play a greater role. However, arguing a greater role does not produce actual commitments. Hence an important question for US planners is when will the EU actually commit forces to regional security missions. An analysis of EU security policy and military engagement decisions can identify the core factors that persuade EU members to approve regional security missions. The three EU military engagement cases chosen for this study were: the 2006 EU military operation in the Democratic Republic of the Congo (EUFOR RD Congo), the EU decision not to commit forces to Lebanon in 2006, and EU decision to enforce a maritime zone off the coast of Somalia (EUNAVFOR Atalanta). The case studies were selected based upon the recent maturity of EU security policy and capability. The cases also illustrate the range of situations in which the EU might be asked to act. EU security policy has evolved to embrace regional security missions but the three cases show there are specific conditions that must apply when the EU makes a decision. There must be (1) clear EU interests, (2) an international basis for mission legitimacy, and (3) a willingness on the part of Britain, France, and Germany, to provide the operational leadership. Additionally, the EU will not intervene in open armed hostilities; that is, the intervention will enforce a settlement, it will not produce a settlement. Understanding the criteria under which the EU might consider military operations can help U.S. strategic and operational planners develop “economy of force” approaches that complement U.S. and EU interests. The analysis can also provide a common frame of reference for senior U.S. decision-makers concerning EU’s aspirations to be a credible global security player.