U.S. Air Force F-16 Fighting Falcons from the 18th Aggressor Squadron at Eielson Air Force Base, Alaska, refuel behind a KC-135 Stratotanker assigned to the Pennsylvania Air National Guard’s 171st Air Refueling Wing, while flying over the Joint Pacific Alaska Range Complex May 11, 2015, during Red Flag-Alaska (RF-A) 15-2. RF-A allows participating units to exchange tactics, techniques and procedures as well as improve interoperability. (U.S. Air Force photo by Staff Sgt. Shawn Nickel/Released)