New research shows that China retains a very narrow edge over the United States as South-East Asia's most influential partner, with experts predicting it will soon pull further ahead as the Trump administration's policies begin to bite in the region.
The Lowy Institute's 2025 South-East Asia Influence Index maps the relative strength of outside players in the rapidly growing and fiercely contested region, including the US, China, Japan, South Korea, Australia, the United Kingdom, and Russia.
The paper finds that China has a clear lead as the most influential player in six out of the 11 countries in South-East Asia, including Myanmar, Laos, Cambodia, Brunei, Malaysia and Indonesia
[map]That makes it the most significant power overall in the region, although it is not a dominant force.
The US is trailing only just behind China in its influence, maintaining a clear lead over Beijing in both Singapore and the Philippines, and almost matching it in Vietnam and Thailand.
But the Lowy Institute's Sussanah Paton said US influence in the region was already eroding, and that Donald Trump's moves to hit South-East Asia with hefty tariffs — while slashing foreign aid and tightening migration — would accelerate the region's drift towards China.
"The actions of the Trump administration are only likely to exacerbate that trend … all of this is likely to further undercut US standing in South-East Asia in the years ahead," she said.
"Imposing significant tariffs is not positive for US influence in the region."
China's influence not 'hegemonic'
The index finds that China's greatest strengths are in trade and economic engagement with South-East Asia — it is the region's leading export market, responsible for around 26 per cent of the region's imports and an increasingly important source of private investment.
It is also the region's top diplomatic partner, maintaining an extensive network of embassies and keeping up a steady tempo of high-level political engagement across the region — in stark contrast to the US.
But Ms Paton said China lagged in other areas, trailing the United States in cultural influence and maintaining relatively weak defence networks across South-East Asia.
"We don't describe China as hegemonic in its influence … it's not the leading partner for South-East Asia across all dimensions of influence," she said.
"For example, when it comes to defence networks, China is making some efforts to establish more substantial defence partnerships, but it's still fairly limited and much less than that of the United States."
The index finds that other external countries trail well behind the US and China when it comes to influence, with Japan clearly ahead of the rest of the pack.
"It's the only other external partner that has an influence across the whole region and on different dimensions — so as an economic, security and economic partner, and a source of cultural influence," she said.
The next "tier" of countries includes India, South Korea and Australia.
Ms Paton said while Australia performed strongly as a defence partner and an important source of diplomatic influence, its economic and cultural power continued to lag in the region.
"That suggests that although the Australian government is highly focused on the region, the same isn't necessarily true of Australian businesses or broader communities," she said.
The index also stressed that while many countries outside the region remain intent on maximising their influence, collectively, South-East Asian nations still mattered more to each other than any external partners.
