The security environment facing the U.S. and NATO in Europe is changing in fundamental ways, including a steady growth of security challenges emanating from Europe’s southern periphery-around the Mediterranean and beyond. This study explores this phenomenon, with special attention to transregional risks, Turkey’s Alliance role and need for redefinition, the risk of a Greek-Turkish conflict, the Mediterranean dimension of NATO adaptation, and what these issues might mean for U.S. and NATO strategy. Areas for future research include lessons of Kosovo for basing and access, the role of air power based in Turkey,a nd potential USAF contributions to Greek-Turkish risk reduction.