U.S. Air Force Staff Sgts. Corie Flores and Ryan Vottero, 633rd Security Forces Squadron Base Defense Operations Center operators performs a tactical stack up before entering a mock control tower building during Combat Readiness Training at Langley Air Force Base, Va., June 27, 2016. Team movement is one of eight blocks of instruction taught at CRT acting as a refresher/prerequisite for predeployment training. (U.S. Air Force photo by/Tech. Sgt. Daylena S. Ricks)