U.S. Air Force F-15E Strike Eagles wait to receive fuel from a KC-135R Stratotanker during exercise Red Flag 15-1 on their way to Nellis Air Force Base, Nev., Jan. 23, 2015. The F-15 crews are assigned to the 4th Fighter Wing. Red Flag provides a series of intense air-to-air scenarios for aircrew and ground personnel to increase their combat readiness and effectiveness for real-world operations.