Staff Sgt. Brett Silmon, 319th Security Forces Squadron military working dog handler, commands his K9 partner, Arco, to attack Staff Sgt. Richard Lynn, a simulated aggressor, during a training exercise on Sept. 11, 2014, on Grand Forks Air Force Base, North Dakota. Silmon and Arco practice patrol maneuvers to maintain quick responsiveness and listening skills. (U.S. Air Force photo/Senior Airman Xavier Navarro)