The United States is open to the possibility of joint naval patrols with the Philippines in the South China Sea, a U.S. diplomat said Wednesday, stressing it would continue to exercise "freedom of navigation" in the disputed waters.

China claims most of the South China Sea, through which more than $5 trillion of world trade is shipped every year. Vietnam, Malaysia, Brunei, the Philippines and Taiwan have rival claims.

A U.S. Navy destroyer sailed within 12 nautical miles (22 km) of an island claimed by China in the South China Sea on Saturday to counter efforts to limit freedom of navigation, the Pentagon said, prompting an angry reaction from Beijing.