Tam-Sang Huynh, an international-relations lecturer at the Ho Chi Minh City University of Social Sciences and Humanities, said Vietnam was being courted by regional powers due to its location in the centre of Southeast Asia and its status as “a geopolitical swing state”.

“Southeast Asia will continue to bear a heavy burden of being a minefield for great-power competition,” he added.

The East Asian nation is also now said to be discussing possible arms sales to Vietnam as the latter seeks to modernise its arsenal.

The US and Vietnam established their “comprehensive partnership” a decade ago, and are now rumoured to be looking into the possibility of upgrading this to a “strategic” one.

But Hanoi has so far remained cautious, mostly because of concerns that doing so might upset Beijing or lead to a Chinese reprisal.

Khang Vu, a PhD candidate in political science at Boston College in the US with a focus on East Asian security, said that while the wooing of Vietnam by major powers in recent weeks was a positive outcome of Hanoi’s “diplomatic balancing”, “Vietnam’s number one priority is to maintain a stable relationship with China to lower the risks of a military conflict”.

“Vietnam has largely stuck to a neutral foreign policy of diversification and multilateralisation to ensure it does not upset China while widening the scope of its diplomatic engagements with other powers,” he said.

Vu added that as the weaker partner militarily, Vietnam has to “garner more support whenever China bullies it at sea” and seek out alternative security options in case relations with Beijing sharply deteriorate.

The Chinese research ship and its escort operated for nearly a month, conducting “normal research activities in maritime waters under China’s jurisdiction”, according to a Chinese foreign ministry statement, before returning to the island province of Hainan.

Carl Thayer, a Southeast Asia regional specialist and emeritus professor at The University of New South Wales, said Vietnam was using high-level diplomacy as leverage amid US-China tensions.

“Each of Hanoi’s strategic partners has to evaluate the costs of not cooperating with Vietnam, such as conceding influence to a rival,” Thayer said, adding that the Vietnamese initiative to engage major powers diplomatically was not just aimed at reducing regional tensions but also strengthening its role in regional security.

Prashanth Parameswaran, founder of the weekly Asean Wonk newsletter and a fellow at the US-based Wilson Centre think tank, said major powers see Vietnam as a militarily capable, diplomatically active, economically significant and politically stable country.

“Vietnam’s strategy of cultivating diverse relationships helps it manage risks and maximise opportunities, but this multidirectional foreign policy approach also requires careful calibration which is more challenging to do when the geopolitical environment worsens,” he said.