Drak, military working dog, demonstrates an attacking movement on Staff Sgt. David Garver, 633d Security Forces Squadron military working dog trainer, during validation training 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)