A Vietnamese protester holds a banner in a rally against Beijing's deployment of an oil rig in the contested waters of the South China Sea, outside the Chinese Embassy in Hanoi.

A Vietnamese protester holds a banner in a rally against Beijing's deployment of an oil rig in the contested waters of the South China Sea, outside the Chinese Embassy in Hanoi. Photo: AP

Hong Kong: China and Vietnam appear to have reached at least a temporary impasse over a giant drilling rig sent by a state-controlled Chinese oil company to a site in the South China Sea between the Vietnamese coastline and a cluster of disputed islands, as the confrontation has continued to raise thorny issues of international law.

Colonel Pham Quang Oanh, deputy chairman of the political department of Vietnam's Coast Guard, said that as many as 15 Chinese ships had sprayed a Vietnamese vessel at the site with water cannons on Monday. He denied a report in Vietnamese media that the vessel had used water cannons to fire back.

Over the weekend, Prime Minister Nguyen Tan Dung of Vietnam asked fellow leaders of the Association of Southeast Asian Nations for support in confronting China. But the government of Myanmar, the host of the meeting, issued only an oblique statement on Monday expressing "serious concern" over the developments in the South China Sea, without mentioning China by name.

Hua Chunying, spokeswoman for the Chinese Foreign Ministry, said at a briefing Monday that China and Vietnam had "14 communications" last week concerning the oil rig, and that they were continuing to communicate about it. She was not specific about what was said, or what the basis of the communications had been.

Diplomats in Beijing said they knew of no substantive talks between China and Vietnam. A senior diplomat, who declined to be named for fear of alienating the Chinese, said he understood that the head of the Communist Party in Vietnam had offered to visit Beijing to speak with President Xi Jinping, but the overture had been rejected.

China's confrontation with Vietnam is drawing particular attention around the region because Vietnam had been following a diplomatic path meant to head off such problems.

Vietnam and China reached bilateral understandings in 2011 and again last year on a framework for discussing maritime issues so that they would not turn into confrontations. The two countries have also reached agreements on their shared land border and on maritime rights in the Gulf of Tonkin.

By contrast, other countries in the region, notably the Philippines with backing from the United States, have strongly resisted engaging in bilateral talks with China out of concern that they would be bullied by Beijing. They sought multilateral talks instead.

The Philippines has also begun a legal case against China before a United Nations tribunal, seeking arbitration of territorial claims in the South China Sea under the UN Convention on the Law of the Sea. China is a signatory to the convention, although it has not approved a side agreement accepting mandatory binding arbitration of disputes.

China has ignored the Philippine case, refusing even to send lawyers to argue its side.

Officials and scholars in Vietnam have been debating for at least a year whether Vietnam should also demand arbitration under the Law of the Sea convention. Peter Dutton, the director of the China Maritime Studies Institute at the US Naval War College, said that seeking arbitration could help Vietnam offset the weight of China's greater military power, and that it would complement other steps Vietnam may take.

"The Philippines used the law to try to equalise their situation," he said. "The question for Vietnam is whether they feel the need to use the law to add to their dispute resolution" efforts.

Jerome Cohen, a longtime specialist in Chinese legal issues who is now a law professor at New York University, said that Vietnam had understandably been less quick than the Philippines to mount a direct legal challenge to Beijing. Unlike the Philippines, Vietnam is not shielded from China's army by the sea, and Vietnam has no comprehensive defence agreement with the United States.

"They have a lot of reasons not to be as bold as the Philippines," Mr Cohen said.

David Zweig, the director of the Center on China's Transnational Relations at the Hong Kong University of Science and Technology, said that China's tough stance now toward Vietnam could imperil Chinese diplomatic goals elsewhere in the region.

"If China can't work with Vietnam after a bilateral agreement, how are they going to persuade anyone to agree to bilateral agreements over multilateral agreements?" he said.

Mr Zweig said that China's assertive stance could also backfire if it prompts Southeast Asian nations to embrace President Barack Obama's strategic shift of American policy toward Asia. "All of these actions reinforce the countries of Southeast Asia to welcome the pivot," he said.

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