A US warship sailed within 12 nautical miles of an island claimed by China in the South China Sea, prompting quick condemnation from Beijing on Saturday.
US navy's guided-missile destroyer USS Curtis Wilbur sailed near Triton Island in the Paracel Islands in the South China Sea, an operation Washington claims was aimed at countering efforts to curb freedom of navigation in the region, Reuters reported.
"This operation challenged attempts by the three claimants - China, Taiwan and Vietnam - to restrict navigation rights and freedoms," Pentagon spokesman Captain Jeff Davis said.
In October, guided-missile destroyer Lassen had sailed near one of the man-made islands China is building in the dispute waters.
China reacted angrily on Saturday and issued a statement saying Chinese ships confronted the US vessel, and "warned and expelled it swiftly".
However, the Pentagon spokesman said no ships from China's military were in the vicinity.
The US action "severely violated Chinese law, sabotaged the peace, security and good order of the waters, and undermined the region's peace and stability," Defence Chinese Ministry spokesman Yang Yujun said, Xinhua News Agency reported.
Ying said the US action was highly irresponsible and that China's armed forces will take measures to safeguard the country's sovereignty and security.
China, which claims sovereignty over the whole of South China Sea, took the control over the Triton island in 1974, defeating Vietnamese forces in the Paracels. Vietnam lost more than 70 soldiers in the Chinese military offensive for the Paracels.
In 2014, China set up a drilling rig in waters near the Paracel Islands and in 2015 satellite images showed Beijing was building an airstrip on land reclaimed around the Spratlys.
More than 20 people were killed in nation-wide anti-China protests in Vietnam after China's rig move. China withdrew the rig after conducting drilling for two months.
The dispute and strategic points
The overlapping claims of sovereignty over two island chains by China, Taiwan, Malaysia, the Philippines, Vietnam and Brunei has made the South China Seas a sensitive region. The United States has strategic interests in the region as well, and it offers a counter balance against Beijing's influence in the waters.
The US adopts a stern line against China's land reclamation, construction and militarisation in these islands but China staunchly defends its claim to sovereignty in the region.
The US too has US military facilities in Southeast Asia -- Philippines and Thailand. It also has stationed its Poseidon sub-hunters and electronic warfare platforms in Malaysia and Singapore.
The mostly uninhabited islands in South China Sea are of crucial strategic importance. The two major island chains -- the Paracels and the Spratlys -- are thought to harbour natural resources around them. China hopes the oil and natural gas reserves in the region could ensure its energy security.
The sea is also a major trading route through which ship-borne trade worth $5 trillion passes every year.
For energy hungry China the sea routes in South China Sea are crucial as most of its imported oil flows through these routes.
Control over the territory allows Beijing to prevent the US from expanding its sphere of influence in the region.