China rebuked Washington for sending a U.S. guided-missile destroyer close to one of Beijing's man-made islands in the disputed South China Sea, saying it had tracked and warned the ship and called in the U.S. ambassador to protest.
The USS Lassen's patrol on Tuesday was the most significant U.S. challenge yet to the 12-nautical-mile territorial limits China claims around artificial islands it has built in the Spratly archipelago.
Washington's move followed months of deliberation by President Barack Obama's administration and could ratchet up tension in one of the world's busiest shipping lanes and increase strains in U.S.-China relations.
China claims most of the South China Sea, through which more than $5 trillion of world trade passes every year. Vietnam, Malaysia, Brunei, the Philippines and Taiwan have rival claims.
A U.S. defense official said the Lassen also went within 12-mile limits of features in the disputed sea claimed by Vietnam and the Philippines, a U.S. treaty ally. Such "freedom-of-navigation" patrols were expected to become more frequent, the official said.