Chris Brummit

Associated Press

HANOI, Vietnam (AP) — Vietnamese naval vessels and Chinese ships collided Wednesday in the South China Sea as Hanoi sought to prevent Beijing from setting up an oil rig in an area claimed by both nations, a Vietnamese government official said.

The official said no shots were fired and there were no reports of injuries in the incident, the most serious in years between the two countries at sea. If neither side steps down, clashes could break out between the two navies in what has long been regarded as a possible global flashpoint.

China's stationing of the oil rig over the weekend has been seen as one of its most provocative steps in a gradual campaign of asserting its sovereignty in the South China Sea, parts of which are also claimed by Vietnam, the Philippines and other Southeast Asian nations.

Two foreign diplomats said Vietnam dispatched up to 29 armed naval and coast guard ships to areas near the oil rig when it became aware of China's intentions. Citing a Chinese diplomat, one said the Vietnamese deployment was meant to be a "show of force" to get Beijing to withdraw the rig.

All spoke on condition of anonymity because of the sensitivity of the information.

China moved the giant deep-sea oil rig to an area close to the Paracel Islands on May 2 accompanied by a large flotilla of naval vessels. It also announced that no foreign ships would be allowed within a 3-mile (4.8-kilometer) radius of the $1 billion rig.

Vietnam immediately called the deployment illegal and demanded China withdraw the rig, around 220 kilometers (140 miles) off the Vietnamese coast.

The Vietnamese official said Vietnam's ships were outnumbered by the Chinese flotilla escorting the rig.

He said the ships were trying to stop the rig from "establishing a fixed position" at the spot where it wanted to drill.

China's assertiveness along with its growing military and economic might is alarming many smaller countries in the region even as they are aware they need to keep relations open with a vital trading partner.

The United States, which is undertaking a military and economic "pivot" toward Asia in part to counter Chinese influence, shares the concerns of the smaller nations. In a strongly worded statement in Washington on Tuesday, State Department spokeswoman Jen Psaki called China's action "provocative and unhelpful to the maintenance of peace and stability in the region."

Vietnam has limited leverage in dealing with its giant neighbor and vital economic partner. It can't afford damaged ties with Beijing and has no hope of competing with it militarily. While it is no longer as isolated as it once was, the country can't expect much diplomatic help from powerful friends.

"China seems intent on putting down its footprint squarely in contested waters and force Hanoi's hand. It appears a critical juncture has occurred and one would expect Hanoi to be weighing its options," said Jonathan London, a Vietnam expert at the City University of Hong Kong. "Hanoi's back is against the wall, though China's policies — which according to virtually everyone except China are baseless legally — have brought about this situation."

China occupied the Paracel Islands 40 years ago, and 74 U.S.-backed South Vietnamese forces died in a subsequent military clash. The Vietnamese and Chinese navies clashed again in 1988 in the disputed Spratly Islands, leaving 64 Vietnamese sailors dead.

In 1992, China awarded a contract to U.S. energy company Crestone to explore for oil and gas in the Spratly Islands. Vietnam protested the move. Two years later, Vietnam's navy forced the company's oil rigs to leave the area.