The struggle between China and the US defines this century. Even close US allies are torn by a choice—not between the two great powers but in choosing whether to back the US against China or to try to stand aside.

The US-China bilateral relationship ‘is more strained than it has ever been at any other point in the 21st century’, the International Institute for Strategic Studies (IISS) says in its 2025 Asia-Pacific security assessment. Trade, technology and Taiwan set the tone for ‘deep mutual distrust’.

The worst-of-times diagnosis applies even without Donald Trump’s trade tensions. Under Joe Biden last year, the IISS’s 2024 security assessment said US–China relations had gone through their worst period since the establishment of diplomatic relations in 1979.

The dreadful relations under presidents as different as Biden and Trump shows the nature of the struggle. While leaders always matter, this is a systemic fight.

IISS goes to that reality: ‘Joe Biden was the first US president since Jimmy Carter not to visit China. Some tactical improvements were made before Trump’s inauguration, such as the resumption of the military-to-military dialogue and an agreement not to include AI in nuclear decision-making. But these moves on their own are unlikely to significantly alter the strategic direction of the two great powers during Trump’s second term.’

Irrespective of temporary or tactical thaws, IISS concludes that the US will stay fixed on China as what it calls ‘a near-peer adversary’. The risk of misperception and misstep increases, because military and diplomatic mechanisms between the Washington and Beijing are limited and little used.

One of the headline questions in the security assessment is: ‘Can Trump avoid a war with China over Taiwan?’ The US promises it could fight and win a Taiwan war, reporting that China wants to be ready for a 2027 invasion. The IISS judgement is relatively sanguine: ‘Given the traditional risk aversion on both sides, a large-scale war with China over Taiwan is unlikely in the near term, although it is not impossible.’

Leaders stare at that ‘not impossible’ thought, and much else in this century’s big struggle.

At IISS’s annual defence summit in Singapore on the weekend, the Shangri-La Dialogue, French President Emmanuel Macron said that ‘the main risk today is a risk of division of the world and a division between the two superpowers’. Macron said competing for global leadership, China and the US are instructing all other nations, ‘you have to choose your side’. Revisionist countries wanted ‘to impose under the name of spheres of influence’ what would be ‘in reality, spheres of coercion’.

Macron said Europe and Asia had a common interest in autonomy from the two superpowers. While it was a friend and ally of the US, he said, France would do what was essential for ‘strategic autonomy’. This is driven by fear about the strength of US alliance promises, as Macron said:

We live in a time of a potential erosion of long-time alliances whose credibility and clout is under threat. Alliances, by the element of balance they brought, had been essential to maintain stability in Europe and Asia; and the sense that their promise might not be ironclad is ushering in a new instability. We see it every day. And the credibility of the alliances, which is to be confirmed, is a very important point for stability.

Macron’s we-don’t-have-to-choose argument chimes with the traditional approach of the Association of Southeast Asian Nations. Its current chairman, Malaysia’s Prime Minister Anwar Ibrahim, told the dialogue the region was holding its ground: ‘The more we act together, the harder it becomes to be pulled apart by external gravity. Preserving our autonomy is not about resisting others. It is about strengthening ourselves. This, in essence, is what ASEAN centrality is about.’

Anwar said the ASEAN summit in Kuala Lumpur last week had warned of the ‘dangers of unilateral actions, retaliatory tariffs and the growing risk of global fragmentation’. He said a world shaped by ‘fractures and fault lines’ needed open, rules-based trade:

Economic openness is not just about creating prosperity and growth. It is a source of equilibrium, both between nations and within them, to deal with pressing issues that affect the people, such as poverty, social inequities or even the digital divide. Open markets create the kind of mutual exposure between nations that encourages caution, not confrontation. And when this system is disrupted, markets lose their bearings. Investor confidence wavers while financial flows seize up. What began as a commercial rupture becomes a systemic shock. History reminds us that these shifts are rarely gradual.

The Malaysian prime minister’s solution is ‘active non-alignment’ to balance ‘a strong and enduring United States presence in the region’ with ‘vibrant and firm ties with China’.

Anwar’s aim is cooperation without coercion, and balance without bloc politics: ‘Malaysia does not believe in spheres of influence. History has shown that when major powers attempt to divide the world into exclusive zones of control, smaller nations are often left voiceless. Stability does not come from carving up the map, but from creating space for all to participate meaningfully in shaping the order we live in.’