U.S. Marines prepare an MV-22 Osprey for a tail gun live-fire exercise in Southwest Asia, Dec. 20, 2015. The Marines, assigned to Marine Medium Tiltrotor Squadron 268, Special Purpose Marine Air-Ground Task Force-Crisis Response-Central Command, are capable of conducting assault operations as part of a crisis response mission spanning 20 nations in the U.S. Central Command area of responsibility. U.S. Marine Corps photo by Lance Cpl. Clarence Leake