A US Navy guided-missile destroyer sailed within 12 nautical miles of an island claimed by China and two other nations in the South China Sea on Saturday, in an operation the Pentagon said aimed to challenge efforts to restrict freedom of navigation.
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.
Pentagon spokesman Captain Jeff Davis said no ships from China's military were in the vicinity of the USS Curtis Wilbur when it passed near Triton Island in the Paracel Islands.
"This operation challenged attempts by the three claimants - China, Taiwan and Vietnam - to restrict navigation rights and freedoms," Davis said, reflecting the US position that the crucial sea lane should be treated as international waters.
The Navy conducted a similar exercise in October in which the guided-missile destroyer Lassen sailed close to one of China's man made islands, drawing a rebuke from Beijing.
Davis said the latest operation sought to challenge policies that require prior permission or notification of transit within territorial seas. He said the United States took no position on competing sovereignty claims to naturally-formed land features in the South China Sea.
"No claimants were notified prior to the transit, which is consistent with our normal process and international law," Davis said.
The operation followed calls in Congress for the Obama administration to follow up on the October operation.
This month, the chairman of the US Senate Armed Services Committee criticised Obama for delaying further freedom of navigation patrols.
He said that allowed China to continue to pursue its territorial ambitions in the region, including by landing a plane on a manmade island in the Spratly Islands archipelago