HANOI, Vietnam (AP) -- Chinese ships have been ramming into and firing water cannons at Vietnamese vessels trying to stop Beijing from putting an oil rig in the South China Sea, according to officials and video footage Wednesday, in a dangerous escalation of tensions over waters considered a global flashpoint.
Several boats have been damaged and at least six Vietnamese on board them have been injured, officials said. The United States said it was concerned and accused China of ramping up tensions in the area.
"China's decision to introduce an oil rig accompanied by numerous government vessels for the first time in waters disputed with Vietnam is provocative and raises tensions," State Department spokeswoman Jen Psaki said in a statement. "This unilateral action appears to be part of a broader pattern of Chinese behavior to advance its claims over disputed territory in a manner that undermines peace and stability in the region."
Elsewhere in the sea, the Philippines arrested 11 Chinese fishermen for catching endangering turtles, angering Beijing and further exposing regional strains.
China recently has been harassing Vietnam and Philippine vessels and fishermen in the potentially oil- and gas-rich waters it claims almost entirety -- a shaky stance to many international law experts.
But China's deployment of the oil rig on May 1 and the flotilla of escort ships, some armed, is seen as one of its most provocative steps in a gradual campaign of asserting its sovereignty in the South China Sea. With neither country showing any sign of stepping down, the standoff raises the possibility of more serious clashes.
Hanoi, which has no hope of competing with China militarily, said it wants a peaceful solution and -- unlike China -- hadn't sent any navy ships to areas close to the $1 billion deep sea rig near the Paracel Islands. But a top official warned that "all restraint had a limit."
"Our maritime police and fishing protection forces have practiced extreme restraint, we will continue to hold on there," Ngo Ngoc Thu, vice commander of Vietnam's coast guard, told a specially arranged news conference in Hanoi. "But if (the Chinese ships) continue to ram into us, we will respond with similar self-defense."
After China stationed the oil rig, Vietnam immediately dispatched marine police and fishery protection vessels but they were harassed as they approached, Thu said.
Video was shown at the news conference of Chinese ships ramming into Vietnamese vessels and firing high-powered water cannons at them. Thu said the Chinese vessels have done so "dozens" of times over the last three days. He said Vietnam had not carried out any offensive actions of its own close to the rig, about 220 kilometers (140 miles) off the Vietnamese coast.
Chinese Foreign Ministry spokeswoman Hua Chunying told a regular news briefing that the oil rig was in China's territorial waters and therefore drilling is "normal and legal." The country previously said foreign ships would be banned within a 3-mile (4.8-kilometer) radius of the rig.
"The disruptive activities by the Vietnamese side are in violation of China's sovereign rights," she said.
A Vietnamese official who spoke on condition of anonymity because of the issue's sensitivity said earlier that Vietnam's ships were outnumbered by the Chinese flotilla. He said the Vietnamese 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 neighbors even as they are aware they need to keep relations open with a vital trading partner.
Hua said the U.S. has no right to make unwarranted remarks on China's sovereign rights.
Vietnam has limited leverage in dealing with its giant neighbor. While it is no longer as isolated as it once was, the country can't expect much diplomatic or other help from powerful friends. It appears likely to try to rally regional support against China's actions.
"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.
The Philippines has filed a legal challenge to China's territorial claims at a U.N. tribunal, against the wishes of China. Vietnam and other claimant states haven't done that yet.
Tran Duy Hai, vice chairman of Vietnam's national borders committee, didn't rule it out.
"Vietnam will have to use all measures stipulated in the U.N. Charter to defend its interests," he said.