U.S. Air Force Gen. Paul J. Selva, Vice Chairman of the Joint Chiefs of Staff, speaks at the National Defense University (NDU) Graduation at Fort Lesley J. McNair, Washington D.C., June 7, 2018. The NDU Class of 2018 consists of leaders from the U.S. military services, the Department of Defense, other federal government agencies, as well as from the foreign militaries of 66 allied and partner nations. (DoD Photo by U.S. Army Sgt. James K. McCann)