160415-D-DT527-535 SOUTH CHINA SEA (April 15, 2016) U.S. Navy Sailors conduct flight deck operations on the aircraft carrier USS John C. Stennis (CVN 74) as Secretary of Defense Ash Carter and Philippine Secretary of National Defense Voltaire Gazmin (neither pictured) observe as they tour the aircraft carrier as it sails the South China Sea 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)