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.
The U.S. destroyer sailed within 12 nautical miles of Subi Reef, one of seven artificial islands built up by China in the past year.
A Chinese guided-missile destroyer and a naval patrol ship shadowed and gave warnings to the U.S. warship "according to law", China's Defense Ministry said.
The U.S. patrol was a "coercive action that seeks to militarize the South China Sea region" and an "abuse" of freedom of navigation under international law, it said.
China's navy said the "air arm" was also involved, but gave no details.
The official People's Liberation Army Daily said in a front page commentary on Wednesday the United States needed to learn the lessons of the chaos in places like Iraq and Afghanistan, which it said proved how a U.S. show of force never brought stability.
"Cast iron facts show that time and again the United States recklessly uses force and starts wars, stirring things up where once there was stability, causing the bitterest of harm to those countries directly involved," it said.
The U.S. defense official said the USS Lassen was followed at a safe distance by a Chinese ship and no incidents were reported during the 72-mile (115 km) passage.
"I would expect that this becomes a regular operation in the South China Sea," the official said. "This type of operation shouldn't be seen as provocative."
The official said the USS Lassen had been followed for weeks by Chinese vessels before the patrol.
Two other U.S. officials said there was bridge-to-bridge radio communication with the Chinese as the Lassen approached Subi Reef. One of the officials said the Chinese did not shadow the U.S. warship as closely when it came within 12 miles of islands claimed by the Philippines and Vietnam.
U.S. Defense Secretary Ash Carter, testifying to the Senate Armed Services Committee on Tuesday, initially said only that the U.S. Navy had conducted operations in the South China Sea. However, he said under questioning from lawmakers the USS Lassen had passed within 12 miles of a Chinese artificial island.
China's Vice Foreign Minister Zhang Yesui summoned U.S. Ambassador Max Baucus, telling him that the patrol was "extremely irresponsible", the Foreign Ministry said. It said earlier the USS Lassen "illegally" entered waters near islands and reefs in the Spratlys.
Foreign Ministry spokesman Lu Kang told a daily briefing on Tuesday that, if the United States continued to "create tensions in the region", China might conclude it had to "increase and strengthen the building up of our relevant abilities".
Lu did not elaborate, except to say he hoped it did not come to that. His comments suggested China could further boost its military presence in the South China Sea.
In Washington, U.S. State Department spokesman John Kirby told a regular briefing: "Setting this aside, the U.S.-China relationship is vitally important and one we want to see continue to improve and to grow for the benefit of both our countries, not to mention the region."
Subi was submerged at high tide before China began a dredging project to turn it into an island in 2014.
Under the U.N. Convention on the Law of the Sea, 12-nautical mile limits cannot be set around man-made islands built on previously submerged reefs.
Pentagon officials say the United States regularly conducts freedom-of-navigation operations around the world to challenge excessive maritime claims. The U.S. Navy last went within 12 miles of Chinese-claimed territory in the Spratlys in 2012.
China traveled within 12 nautical miles of the U.S. controlled Aleutian Island about six weeks ago, the defense official said.
The USS Lassen patrol was carried out just weeks before a series of Asia-Pacific summits that Obama and Chinese President Xi Jinping were expected to attend.
Security experts have said Washington's freedom-of-navigation patrols would have to be regular to be effective, given Chinese ambitions to project power deep into maritime Southeast Asia and beyond.
Some have said China would likely resist attempts to make such U.S. actions routine. China's navy could, for example, try to block or attempt to surround U.S. vessels, risking an escalation.
Washington worries that China has built up its outposts with the aim of extending its military reach in the South China Sea. China says they will have mainly civilian uses and undefined defense purposes.
Xi surprised U.S. officials after a meeting with Obama in Washington last month by saying that China had "no intention to militarize" the islands.