Cheyenne Mountain exercises 'button-up'
Airman 1st Class Derrick Warfield manually locks a 25-ton blast door at Cheyenne Mountain Air Force Station, Colo., during a recent operational readiness inspection. Looking on are Senior Airman Anthony Williams and two contractors from the 721st Mission Support Group civil engineer division. The two Airmen are with the 721st Security Forces Squadron. (U.S. Air Force photo/1st Lt. Jeff Crepeau)