BEIJING (NYTIMES, CHINA DAILY/ASIA NEWS NETWORK) - China's military said that it had dispatched warships to challenge two US Navy vessels that sailed through waters in the South China Sea that China claims as its own.

The Chinese confronted the US ships and warned them to leave, the Ministry of National Defence said in a statement posted on its website on Sunday (May 27), but other details of the encounter were not immediately clear.

The US vessels - the Higgins, a destroyer, and the Antietam, a cruiser - passed within 12 nautical miles of the Paracel Islands, an archipelago in the northern part of the disputed waters of the South China Sea off the coast of Vietnam.

The chief spokesman for China's Ministry of National Defence, Senior Colonel Wu Qian, said that the United States "gravely violated Chinese sovereignty."

On Sunday night, Foreign Ministry spokesman Lu Kang said in a statement that the US warships trespassed into China's territorial waters off the Xisha Islands without permission of the Chinese government, and the Chinese navy identified the US warships, warned and expelled them.

The Paracel Islands are known as Xisha in Chinese.

Mr Lu said that the islands are are China's inherent territory, noting that in accordance with the Law of the People's Republic of China on the Territorial Sea and the Contiguous Zone, the Chinese government promulgated the baseline of the territorial sea off the islands in 1996.

"The Chinese side strongly urges the US side to immediately stop such kind of provocative operations that violate China's sovereignty and threaten China's security," Mr Lu said, noting that the Chinese side will continue to take all necessary measures to defend national sovereignty and security.

The high-seas confrontation, while not unprecedented, came as tensions have been rising between the United States and China on a number of fronts, from trade to the on-again-off-again talks with North Korea over its nuclear programme.

In recent months, China has appeared more determined to defend its claims in the South China Sea, reinforcing and arming its bases in the Paracel Islands and farther south in the Spratly Islands, even though the various islands, reefs, shoals and other outcroppings are also claimed by Vietnam, the Philippines, Taiwan and others.

On May 18, China announced that it had for the first time landed its H-6K strategic bomber on an outpost in the Paracels, Woody Island. Earlier in the month, the United States also formally protested the deployment of missiles and radar equipment on three artificial islands China has built in the Spratly Islands.

US officials accused Beijing of breaking a promise that Chinese leader Xi Jinping made in 2015 when he said China did not intend to militarise the disputed territories.

In retaliation for the deployment, the Pentagon last week rescinded an invitation for China to participate in a multinational naval exercise this summer near Hawaii.

China, whose claims on the islands in the Paracel and Spratly Islands are not recognised, argues that passage within 12 nautical miles constitutes a violation of the country's territory under the United Nations Convention on the Law of the Sea.