Defense Secretary Ash Carter, right, exchanges greetings with Navy Vice Adm. William Brown, deputy commander of U.S. Transportation Command, upon arriving on Scott Air Force Base, Ill., Aug. 26, 2015, for an assumption-of-command ceremony. Carter delivered remarks at the ceremony, during which Air Force Gen. Darren W. McDew assumed leadership of U.S. Transportation Command. DoD photo by U.S. Air Force Master Sgt. Adrian Cadiz