track the US warships. If they, instead of passing by, stop for further actions, it is necessary for us to launch electronic interventions, and even send out warships, lock them by fire-control radar and fly over the US vessels," it said.
It added that: "At present, no country, the US included, is able to obstruct Beijing’s island reclamation in the region."
But despite the Chinese rhetoric, analysts said more such US manoeuvres could be expected.
Beijing’s so far limited response showed that it had had "its bluff called", said Rory Medcalf, director of the international security programme at the Lowy Institute in Sydney.
"The US and its allies and partners should now help the Chinese leadership in saving face, by emphasising that freedom of navigation operations are normal, not extraordinary," he said. China’s defence ministry said in a statement it had sent a "Lanzhou" missile destroyer and another ship to warn the USS Lassen.
It added that the US actions had "damaged trust" and said China would take "all necessary measures" to maintain national security.
There have been repeated confrontations in the area between Chinese vessels and boats from some of its neighbours who assert rights to the waters, particularly the Philippines and Vietnam. Both are members of the Association of Southeast Asian Nations, which has long called on China to negotiate a code of conduct in the region, as are fellow claimants Brunei and Malaysia. Taiwan also makes claims over part of the sea.
Manila has infuriated the world’s second-largest economy by taking the dispute to a United Nations tribunal, and Philippine President Benigno Aquino said the US action demonstrated that "the balance of power says that there is not just a single voice that must be adhered to".
Beijing’s reclamations have been seen as an attempt to assert its claims by establishing physical facts, but Aquino said: "There is no de facto changing of the reality on the ground."
Beijing has repeatedly said the construction work is mainly for civilian purposes.
But satellite images of the islands published by the Washington-based Centre for Strategic and International Studies show that Beijing has reclaimed millions of square metres of land in the Spratlys, known as Nansha in Chinese.
The pictures also show a host of facilities with the potential for military applications being developed, including as many as three runways -- at least one of them 3,000 metres (10,000 feet) long.
The US, which is engaged in a foreign policy "pivot" to Asia, and China, which has the world’s largest military and is expanding the reach of its navy, are jockeying for position in the Pacific.
The sail-by was "long overdue", said Bonnie Glaser, a senior China expert at CSIS, adding that the exercises "should be done quietly, regularly, and often".
"There should be no media fanfare," she added. "The way this has been handled has left the Chinese believing that the US is challenging its sovereignty rather than simply exercising freedom of the seas."