U.S. Air Force Airman Juan Luna, 94th Aircraft Maintenance Unit crew chief, reviews technical orders, while preparing to launch an F-22 Raptor during Red Flag 17-4, at Nellis Air Force Base, Nev., August 14, 2017. Red Flag is a realistic combat training exercise involving the air, space and cyber forces of the United States and its allies. (U.S. Air Force Photo/Staff Sgt. Carlin Leslie)