Master-at-Arms Seaman Craig Libbs, right, and Master-at-Arms 2nd Class Brian May, both dog handlers assigned to the Navy Region Southwest K-9 Unit at Naval Base San Diego, train their military working dog, Apoch, during a patrol exercise. Military working dogs are trained to provide deterrence, patrol and detection services. (U.S. Navy photo by Mass Communication Specialist 2nd Class Shannon Heavin/Released)