China has warned a US Navy guided-missile destroyer to keep away from a group of manmade islands it has built in the disputed South China Sea.
Beijing says it followed and challenged the USS Lassen as it sailed within 12 nautical miles of Subi Reef around the islands in the Spratly archipelago.
China says it owns the waters in some of the world’s busiest sea lanes, a claim disputed by other nations.
Vice Foreign Minister Zhang Yesui summoned US Ambassador Max Baucus, telling him the “illegal” US patrol was “extremely irresponsible”, said Beijing.
The Foreign Ministry said in a statement: “The actions of the US warship have threatened China’s sovereignty and security interests, jeopardised the safety of personnel and facilities on the reefs, and damaged regional peace and stability.
“The Chinese side expresses its strong dissatisfaction and resolute opposition.”
US Defence Secretary Ash Carter confirmed Tuesday’s patrol while testifying to the Senate Armed Services Committee.
American defence officials said their warship had sailed in the disputed area and was followed at a safe distance by a Chinese ship.
They said it would be the first in a series of freedom-of-navigation exercises aimed at testing China’s territorial claims.
The US denies targeting China, saying future patrols could take in areas that Vietnam and the Philippines have built up interests in.
Philippine President Benigno Aquino said he supported the US naval manoeuvres.
Speaking in Washington, Indonesian President Joko Widodo urged all parties to exercise restraint.
The White House says the US has already made clear to China how important Washington considers the free flow of commerce in the South China Sea to be.
The US was last within the zone in 2012 – it is the first time it has been within 12 miles of the seven Chinese outposts since Beijing began building the reefs up at the end of 2013.
China has been piling sand on the reefs and atolls before adding buildings, ports and airstrips big enough to handle bombers and fighter jets.
Beijing claims most of the South China Sea, through which more than $5trn (£3.3trn) of world trade passes every year.
Under UN law, 12-nautical mile limits cannot be set around manmade islands built on previously submerged reefs.
Vietnam, Malaysia, Brunei, the Philippines and Taiwan have rival claims.