From left, Secretary of Defense Chuck Hagel, U.S. Air Force Gen. Paul J. Selva and Gen. William M. Fraser III stand at attention during Fraser's change of command and retirement ceremony May 5, 2014, at Scott Air Force Base, Ill. Selva assumed command of U.S. Transportation Command from Fraser, who retired from the Air Force after 40 years of service. (DoD photo by Mass Communication Specialist 1st Class Daniel Hinton, U.S. Navy/Released)