Drak, military working dog, reacts to the movement of Staff Sgt David Garver, 633d Security Forces Squadron military working dog trainer, during a demonstration at Langley Air Force Base, Va., April 6, 2011. Langley AFB dog handlers conduct validation training with their military working dogs in order to evaluate the dog’s ability to patrol and detect threats while also protecting service members from hazards in the field. (U.S. Air Force photo by Airman 1st Kayla Newman/Released)