Ellsworth Air Force Base, S.D., Airmen board a commercial aircraft to leave for Green Flag, a combat training exercise at Nellis Air Force Base, Nev., on the flightline of Ellsworth AFB, S.D., May 10, 2012. The focus of Green Flag will be close air support training, in preparation for future combat operations in Southwest Asia. (U.S. Air Force photo by Airman 1st Class Kate Thornton/Released)