The United States has been an economic, diplomatic, and security actor in the Mediterranean for over 200 years. Mediterranean security is set to pose key tests for both NATO and EU strategy in the years ahead. U.S. political and military engagement will be important elements in regional stability. But the relatively diffuse nature of Mediterranean security risks, a substantially reduced permanent military presence, and some marked differences in the European and U.S. approach to the region will complicate policy looking “south.”