The 2014 incident began with a Chinese oil rig operating in disputed waters and ended with accusations from both sides of vessel ramming, as well as mass anti-China protests across Vietnam.

On Wednesday, Chinese foreign ministry spokesman Geng Shuang said China hoped Vietnam would respect China’s sovereignty and jurisdiction over the contested waters, and “not take actions that could complicate the situation”.

A day earlier, Vietnamese foreign ministry spokesperson Le Thi Thu Hang had responded to journalists’ questions with an online statement which did not mention the incident itself, instead referring only to “recent developments in the South China Sea”.

“Vietnamese authorities at sea have been exercising Vietnam’s sovereignty, sovereign rights and jurisdiction in a peaceful and lawful manner to safeguard Vietnamese waters,” the statement said.

And when Vietnam’s Prime Minister Nguyen Xuan Phuc visited the Vietnamese coastguard headquarters in Hanoi on July 11, at the height of the stand-off, his country’s state media also made no mention of the incident.

A statement about the visit published on the coastguard website said Nguyen had told sailors on board the Vietnamese vessels to “stay vigilant and ready to fight” and to be aware of “unpredictable developments”.

Collin Koh, research fellow with the Maritime Security Programme at Singapore’s S. Rajaratnam School of International Studies, said Hanoi was clearly muting public mention of the issue.

Vietnam’s avoidance of so-called “megaphone diplomacy” was plausibly aimed at preventing an escalation of tensions as a result of public outcry, he said, pointing to the impact on investor confidence which had occurred in 2014 as a result of the anti-Chinese protests.

While investment eventually recovered, it was not before the protests turned deadly and Chinese-owned factories were attacked.

“Moreover, both countries have since repeatedly agreed to “properly manage” their disputes so I surmise that could mean both parties have agreed not to let such rows boil over into the public domain, provoking nationalistic hype and sentiments that could get out of control,” Koh said.

A trip to China by Vietnam’s National Assembly Chairwoman Nguyen Thi Kim Ngan last week had also given both Hanoi and Beijing an opportunity to contain the flare-up, he added, saying it was also in China’s interests to avoid escalating the situation.

China has been trying the establish a narrative that all is well in the South China Sea and all parties concerned can manage the disputes on their own, Koh said.

To support that narrative, China has been promoting negotiations with the Asean nations on a code of conduct for the South China Sea.

Collision highlights need for South China Sea code

There is a consequent imperative for all rival claimants – including Vietnam, Malaysia and the Philippines – to advance the “status quo” in their favour before the deal, which China hopes to close in 2021, according to Professor Hu Bo, director of China’s South China Sea Strategic Situation Probing Initiative.

“Vietnam has speeded up their oil exploitation in the Vanguard Reef region and the survey is probably a counter-action by China,” he said. “But I think the situation is under control because all parties would like a deal to be made.”

He predicted the incident would end quietly, as most of the frequent disputes in the South China Sea do.

“The 2014 crisis was a result of a misjudgment, as Vietnam placed too much expectation in external powers,” he said.

Xu Liping, a Southeast Asia expert at the China Academy of Social Sciences, said the rapidly increasing common interests in the area worked to prevent escalation, noting that National Assembly Chairwoman Nguyen’s visit to Beijing during the incident had included an exchange of pledges with Chinese President Xi Jinping to increase cooperation.

“The growth of the Chinese coastguard and navy’s power in recent years has also made the South China Sea countries take a less confrontational stance,” he said.