Chinese Navy officers reacted with annoyance today when it emerged that the United States had sent a destroyer to back up a surveillance vessel in the South China Sea after it was harassed by People’s Liberation Army (PLA) sailors.

The decision by President Obama to send an armed escort for US surveillance ships in the area follows the aggressive and co-ordinated manoeuvres of five Chinese boats on Sunday. The vessels harassed and nearly collided with the unarmed USNS Impecccable.

One unidentified officer quoted in the China Daily newspaper said that the decision was disproportionate. While China’s Foreign Ministry has so far kept tight-lipped on the latest development, the decision to run such a comment so swiftly in the state-run English-language newspaper was a signal of Beijing’s concerns.

One naval source said the PLA had taken note of the latest US move and was watching developments closely.

Another described the deployment of the USS Chung-Hoon, armed with torpedoes and missiles, as a signal of the Pentagon’s intention to “keep on pressing” China in the South China Sea.

He added: “The timing and the extent have gone beyond what you could call proportionate.”

Top Chinese officers accused the unarmed US Navy ship that it disturbed last Sunday of being on a spying mission. They said they had made repeated representations to the United States to stop sailing so close to Chinese waters and within its exclusive economic zone.

The US keeps a close eye on China’s arsenal, including its fleet of submarines in the area. Washington says the confrontation occurred in international waters, but Beijing claims nearly all the South China Sea as its own, putting it in conflict with five other nations that have claims over different parts of the waters.

The episode complicated fragile military relations between the US and China, which appeared to have improved after the two held defence talks in Beijing last month. President Obama yesterday called for more military dialogue with China to avoid similar incidents after a meeting with Chinese Foreign Minister Yang Jiechi, the White House said.

“The President also stressed the importance of raising the level and frequency of military-to-military dialogue,” it said.

A hotline was established between the Chinese Defence Ministry and the Pentagon in April last year, but it was not used during or after Sunday’s standoff, defence officials said.

This is far from the first time the US Navy has sent vessels to patrol off China in recent years. Many have wielded far more potent fire power.

In November 2007, after China cancelled a port call by the American Kitty Hawk aircraft carrier to Hong Kong, the Pentagon ordered the group to sail through the narrow Taiwan Strait, in a move that was certain to anger Beijing. The previous such transit was in 2002, by the USS Constellation and its battle group.

In July and August 1995 - after China carried out missile tests targeting waters around Taiwan to try to intimidate the rulers of the island it sees as a renegade province - the USS Nimitz sailed through the Taiwan Strait. In March 1996, when China carried out another round of missile tests off Taiwan, the United States sent two aircraft carrier groups - the Independence and the Nimitz - to waters off Taiwan, but they stayed out of the narrow strait to avoid any clash.

Fu Mengzi, assistant president of the China Institute of Contemporary International Relations, said the latest incident should be interpreted separately from President Obama's China policy and was due to the influence of American military officers.

He told the China Daily: “Obama seeks cooperation with China. But some hawkish US military officers don't like it, which led to the spat over the sea confrontation."

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