Two F-15E Strike Eagles wait to receive fuel from a KC-135R Stratotanker Jan. 23, 2015, on their way to Nellis Air Force Base, Nev., in support of Red Flag 15-1. The exercise, featuring aircraft from 21 different Air Force squadrons, offers realistic combat training involving the air, space and cyber forces of the U.S. and its allies. The F-15s are assigned to the 4th Fighter Wing and the KC-135R is assigned to the 916th Air Refueling Wing. (U.S. Air Force photo/Airman 1st Class Aaron J. Jenne)