KUALA LUMPUR - The team of eight Chinese coronavirus experts waved flags and gave their thumbs ups when they arrived in Kuala Lumpur 10 days ago, and the cameras would have probably caught their wide grins if not for the masks they had on.

Such is the face of Beijing's "mask diplomacy" - more cynical observers call it "virus diplomacy" - that has seen medical aid sent to over 120 countries worldwide, including most of South-east Asia.

But this cheerful front comes amid an escalating standoff between China and other claimants, including Malaysia, over disputed waters of the South China Sea.

On April 16, China's Haiyang Dizhi 8 survey ship, reportedly flanked by more than 10 vessels, began shadowing a drillship contracted by Malaysian state oil firm Petronas to explore for oil off its coast, in waters also claimed by China and Vietnam.

China's move set off the US, which sent at least two warships into the fray. Secretary of State Michael Pompeo accused China of "exploiting" the global focus on the coronavirus by "intimidating other claimants" in the South China Sea.

Analysts say this is Beijing's way of reaffirming the status quo, that is China's dominance in the waters, even as the world is grappling with the pandemic that originated in Hubei province last year.

China claims most of the South China Sea as marked on its "nine-dash-line" map, which is not recognised by its neighbours nor the United Nations.

"The overall scheme of simultaneous heightened South China Sea presence on the one hand and ping-pong virus diplomacy on the other is a continuation of China's long-standing carrot and stick foreign-policy strategy in the region, which previously saw Belt and Road initiatives going hand-in-hand with pushing territorial claims," Singapore Institute of International Affairs' senior fellow Oh Ei Sun told The Straits Times.

Malaysia is among several nations which assisted China in its fight against the coronavirus epidemic, donating 18 million gloves in January.

The Chinese foreign ministry said last month "we will reciprocate their kindness without any hesitation". Aside from the experts whose arrivals last week coincided with a drop in infections locally, Beijing has sent various supplies such as protective gear, testing kits and even highly sought-after ventilators.

Others in the region have also been beneficiaries of Beijing's largesse. The Philippines, Cambodia and Laos received medical expertise and equipment, while Thailand and Indonesia received tonnes of medical supplies.

Malaysia has sought to defuse tensions, with Foreign Minister Hishammuddin Hussein saying the dispute should be resolved peacefully as "the presence of warships and vessels in the South China Sea has the potential to increase tensions that in turn may result in miscalculations which may affect peace, security and stability in the region".

Malaysia's middle-ground approach reflects the balancing act the region is having to negotiate as existing enmity between China and the US over trade has deepened in a blame game over the pandemic.

"I don't think the South China Sea is negotiable for China. But that aside, relations remain cordial. What we should be concerned about is lack of leadership in Asean while China is leveraging the pandemic to promote its 'health Silk Road'," said Dr Cheong Kee Cheok, senior fellow at Universiti Malaya's Institute of China Studies.

The stakes are high for governments in South-east Asia, with the outbreak threatening their people's health, the economy and political stability. It would be tough, therefore, to decline Beijing's generosity and the diplomatic ramifications that come with it.

Malaysian Prime Minister Muhyiddin Yassin - whose two-month-old government has a slim majority in Parliament - is unlikely to cool ties with China, Rajaratnam School of International Studies senior fellow Johan Saravanamuttu told ST, as the spoils of "virus diplomacy comes with the West and US in no position to help".

He added: "China is flouting its soft power. If China develops the vaccine first, Malaysia will have first call, given their collaboration on the virus."