U.S. Air Force Master Sgt. Jonathan Oliver, right, a tactical air control party specialist with the 182nd Air Support Operations Group, Illinois Air National Guard, plays an opposition force during an active shooter exercise in Peoria, Ill., Aug. 14, 2017. The exercise evaluated unit members’ responses to a variety of contingency scenarios. (U.S. Air National Guard photo by Tech. Sgt. Lealan Buehrer)