Two US Navy warships sailed near South China Sea islands on Sunday, two US officials told Reuters, in a move likely to anger China as President Donald Trump seeks its continued co-operation on North Korea.
The operation was the latest attempt to counter what Washington sees as Beijing's efforts to limit freedom of navigation in the strategic waters.
While this operation had been planned months in advance, and similar operations have become routine, it comes at a particularly sensitive time and just days after the Pentagon uninvited China from a major US-hosted naval drill.
The US officials, speaking on condition of anonymity, said the Higgins guided-missile destroyer and the Antietam, a guided-missile cruiser, came within 12 nautical miles of the Paracel Islands, among a string of islets, reefs and shoals over which China has territorial disputes with its neighbours.
The US military vessels carried out manoeuvring operations near Tree, Lincoln, Triton and Woody islands in the Paracels, one of the officials said.
Trump's cancellation of a summit with North Korean leader Kim Jong Un has put further strain on US-China ties amid a trade dispute between the world's two largest economies.
Critics of the operations, known as a "freedom of navigation," have said that they have little impact on Chinese behaviour and are largely symbolic.
The US military has a long-standing position that its operations are carried out throughout the world, including in areas claimed by allies, and that they are separate from political considerations.
Satellite photographs taken on May 12 showed China appeared to have deployed truck-mounted surface-to-air missiles or anti-ship cruise missiles at Woody Island.
Earlier this month, China's air force landed bombers on disputed islands and reefs in the South China Sea as part of a training exercise in the region, triggering concern from Vietnam and the Philippines.
Pentagon officials have long complained that China has not been candid enough about its rapid military build-up and using South China Sea islands to gather intelligence in the region.
