Peter Sheerin, a Pinkerton security guard, checks a driver's identification at the west gate on Barksdale Air Force Base, La., Sept. 15. Beginning Sept. 16, everyone wishing to gain access to the installation between the hours of 10 p.m. and 6 a.m. Fridays and Saturdays must have a valid Department of Defense ID or a Barksdale visitor pass. (U.S. Air Force photo/Senior Airman Chad Warren)(RELEASED)