160415-D-DT527-537 SOUTH CHINA SEA (April 15, 2016) Secretary of Defense (SECDEF) Ash Carter observes flight deck operations as he tours the aircraft carrier USS John C. Stennis (CVN 74) as it sails the South China Sea during a visit to the Philippines April 15, 2016. Carter is visiting the Philippines to solidify the rebalance to the Asia-Pacific region. (U.S. Air Force photo by Senior Master Sgt. Adrian Cadiz/Released)