Europe today is challenging the Westphalian system with a supra-state shifting policy-making from sovereign capitals to the European Union (EU). The final step of this evolution is the EU’s alignment of military capacity, policy, and development under the Common Security and Defense Program (CSDP). The U.S. must determine how to interact with a supra-state organization it is not a member of, but cannot ignore to maximize combined strength. While the U.S. has traditionally managed its European security relationships through NATO or bilaterally with sovereign states, it is time to engage with the EU as a security organization. The U.S. must state unequivocal support for the EU’s security aspirations, recognizing the gain in global security, and then establish a military coordination element within the EU Military Staff to synchronize actions with the EU and help build capacity beyond NATO. Additionally, the U.S., NATO, and the EU must define roles for each actor where they possess a competitive advantage to drive requirements-based acquisitions and avoid duplication of capability at a time when U.S. and European resources are constrained.