Colorado Air National Guard Airmen from the 140th Security Forces Squadron perform a “stacking” maneuver as they train on real world scenarios at Buckley Air Force Base, Colo., Nov. 15, 2015.These types of settings educate Airmen to enter, search, and exit an area while being alert and providing security for others on the team. (U.S. Air National Guard photo by Tech. Sgt. Nicole Manzanares)