The US Navy will send more warships to sail close to artificial islands built by Beijing in the South China Sea, a US official said on Tuesday.
The USS Lassen guided missile destroyer sailed within 12 nautical miles of at least one of the land formations claimed by China in the disputed Spratly Islands chain early on Tuesday local time.
The move infuriated Beijing, which summoned the US ambassador and denounced what it called a threat to its sovereignty. "We will do it again," the official told AFP, speaking on condition of anonymity. "We sail in international waters at a time and place of our choosing."
The USS Lassen sailed through waters claimed by China, the Philippines and Vietnam near Mischief Reef in the Spratlys. The official said the sailing lasted about two hours.
China said two of its vessels had shadowed the USS Lassen. Another US official said there had been "routine" communication between the US and Chinese ships.
Testifying to the Senate Armed Services Committee, US Defense Chief Ashton Carter earlier suggested there would be additional activity within the 12-mile zones around the artificial islands.
"We are acting on the basis that we will fly, sail and operate wherever international law permits and whenever our operational needs require," Carter said.
Tensions have mounted since China transformed reefs in the area - also claimed by several neighbouring countries - into small islands capable of supporting military facilities, a move the US says threatens freedom of navigation.
Washington has repeatedly said it does not recognise Chinese claims to territorial waters around the artificial islands.