Several experts VnExpress spoke to over the last few days said China was using its survey vessels to harass other countries engaging in oil and gas exploration in the South China Sea, weaken the opposition. Vietnam calls the waters the East Sea.

"China is trying to wear down Vietnam’s resolve and that of Vietnam’s international security partners, including its fellow Association of Southeast Asian Nations (ASEAN) member states," said John Blaxland, Director of the Southeast Asia Institute at the Australia National University.

Blaxland was referring to the August 13 return of Chinese oil survey vessel Haiyang Dizhi 8 and escorts to Vietnamese waters in the sea.

The Chinese vessels repeated their infringement of Vietnamese waters barely a week after they had left the nation’s exclusive economic zone (EEZ) and continental shelf on August 7.

Haiyang Dizhi 8's return to its activities off the Vietnamese coast is a political message being sent by China "because a commercial survey should have been over by now," said Gregory Poling, director of the Asia Maritime Transparency Initiative and a fellow with the Southeast Asia Program at the Center for Strategic and International Studies (CSIS), the U.S.

"Beijing will not only harass [Hanoi's oil and gas work] but also engage in its own unilateral exploration in Vietnamese waters to increase pressure," he said.

Poling’s view was echoed by Murray Hiebert, Senior Associate of the Southeast Asia Program at CSIS.

It appears that China is increasingly saying that "all the hydrocarbon resources within the ‘nine-dash line’ belong to it, something it has said for some time but hasn't tried to enforce," Hiebert said.

A pattern of harassment

Hiebert also pointed out that China was using survey ships to disturb exploration activities off the coasts of not just Vietnam, but Malaysia too, even if the activities are in the exclusive economic zones of these countries.

As for the Philippines, in July and August, China has sent two oil survey vessels, Dong Fang Hong 3 and Zhang Jian, to the EEZ of the Philippines, operating 80 sea miles from the Southeast Asian nation’s coast.

"This strategy (sending oil survey vessels to other nations' waters) deepens the disputes (between China and regional nations). No longer is the conflict only over sovereignty over islands and features, now it is also over resources," Hiebert said.

Tuan Luc, a PhD Candidate in the School of Humanities and Social Sciences at the University of New South Wales at the Australian Defense Force Academy, or UNSW Canberra, in Australia, also discussed the threat of China putting an oil rig in the southern part of Vietnam’s sea territory.

He said China would not want to push the situation too far but do what it wants, step by step. Before Vietnam becomes the ASEAN chair in 2020, China would not create any conditions that would prompt Hanoi to join other members of the bloc to reach an agreement on the South China Sea in high-level meetings next year or give the U.S. and its allies more reasons to increase activities in the area, Tuan noted.

He predicted that the Haiyang 8 and its escorts will not stay too long because they will need to add fuel and deal with other logistics problems. But, in the long term, China will keep sending and withdrawing its ships, continuing to challenge Vietnamese forces in the waterway, he said.

Tuan also said that Vietnamese forces should exercise restrain and avoid the kind of tensions between China and the Philippines in 2012 in which China took over the Scarborough Shoal.

Consequences?

Hiebert said that when China keeps making it clear that it does not want to disobey international rules, other countries could resort to some kind of business sanctions.

"The maritime militias involved in harassing Vietnamese vessels off Vanguard Bank are owned by state, provincial, and private companies.

"The U.S., ASEAN, Japan, could impose sanctions against these companies and prevent them from doing business with companies from these countries much like the U.S. and others have done with Russian companies in Ukraine," Hiebert said.

Blaxland stressed the need for persistent resistance to Chinese actions.

"The deployment of survey ships is a clever, albeit cynical, way for China to assert its position, whittling away at the international community’s resolve and slowly adding to their own claims for legitimacy. This is all the more reason why persistent and coordinated but peaceful resistance is necessary.

"It remains in Vietnam’s interests to resist and to strongly protest such actions, enlisting as much support internationally as it can muster," he said.