U.S. Air Force airmen of the 4th Fighter Squadron perform maintenance on an F-16 Fighting Falcon during an exercise at Hill Air Force Base, Utah, March 27, 2014. In conjunction with normal maintenance, airmen assigned to the 388th Fighter Wing participate in Operation Noble Eagle (ONE). ONE was launched after the terrorist attacks on Sept. 11, 2001, and it provided rapid ready fighter aircraft to respond to possible threats. Exercises to practice similar tactics are conducted to ensure readiness and the protection of the U.S. air space. (U.S. Air Force photo by Airman 1st Class Scott Jackson/Released)