Incoming US President Trump is known for his belligerent rhetoric on China. But while his stance on economic competition is clear, his stance on security issues – including defence of Taiwan and guarantees to US military allies like the Philippines – is not. Meanwhile, despite ongoing corruption scandals Beijing is proceeding apace with military modernization, its aim being to outclass the US in the East and South China Seas while also expanding and modernizing its nuclear arsenal.
For both China and the US, the strategic calculation in the Indo-Pacific is ultimately underpinned by the risk of war. President Xi Jinping set out China’s ‘red lines’, including its claims to Taiwan, in his final communication with US President Biden at APEC last November.
He also emphasized that the ‘Thucydides trap’ – the idea that a rising and established power will eventually come to blows – is not inevitable. Beijing’s ideal scenario is to achieve its territorial goals in the East and South China Seas without Washington getting involved.
US ambiguity going from strategic to unintended
Washington has long pursued ‘strategic ambiguity’ over Taiwan, calculating that lack of clarity over whether it would intervene would be sufficient to deter Beijing from attacking and Taipei from declaring independence. This is distinct from its formal defence partnerships in the region, including with Japan, South Korea and the Philippines, which commit both parties to mutual assistance in the event of conflict.
While Trump has favoured China hawks such as Marco Rubio and Mike Waltz as picks for his cabinet, he has also criticized Taiwan for failing to pay its way on defence. He is unenthusiastic about involving the US in foreign wars. And Elon Musk, another influential pick for the new administration, has extensive business interests in China. The upshot is that the incoming administration’s stance on China is fundamentally unclear – although the ambiguity is now more unintended than strategic.
This increases the risk of accidental escalation over flashpoints like Taiwan and the South China Sea. Beijing could perceive Trump’s ambiguous stance as a lack of resolve. At the same time, Trump’s more transactional or even antagonistic attitude towards US defence partners raises the prospect of this ambiguity spreading to formal regional commitments, creating opportunities that China could exploit.
Taiwan and the South China Sea
Beijing has significantly increased pressure on Taiwan since the accession of President Lai Ching-te, holding three major military drills last year, rehearsing operations including the quarantine of Taiwanese ports. Meanwhile, China has territorial disputes with various countries in the South China Sea. Tensions with the Philippines, a US military ally, have escalated the most as Chinese tactics have become increasingly aggressive.
In both areas, Beijing has kicked off the year with demonstrations of capability and resolve. According to the Research Project on China’s Defense Affairs (RCDA), which monitors People’s Liberation Army (PLA) activity around Taiwan, more PLA aircraft were detected in the first eight days of 2025 than in the whole of January 2024. Meanwhile, the Chinese coast guard’s largest vessel was sent to the Philippines’ exclusive economic zone (EEZ), prompting protest from Manila.
Beijing’s strategy and the risks of US ambiguity
Beijing’s actions are part of a pattern of normalizing the continuous presence of Chinese vessels and aircraft – and these grey-zone tactics pose a significant challenge to US defence commitments. The PLA massively outnumbers and outclasses the militaries of Taiwan and the Philippines, allowing Beijing to gradually push further in its operations and constraining the ability of its counterparts to respond.
Beijing’s strategy appears to be to ramp up pressure until a US response becomes next to impossible without escalation. When it comes to Taiwan, where Beijing’s objective is not just the assertion of maritime claims but eventual conquest, the success of such tactics would involve wearing down Taiwan’s resolve and confidence in US assistance.
It would also make US intervention extremely difficult – ultimately requiring the presence of US forces around Taiwan, which would likely cross Xi’s red line and risk open conflict.
If Beijing concludes that the incoming US administration’s ambiguous stance indicates that Washington is unlikely to intervene, it may decide to increase the intensity of its operations accordingly. In the South China Sea this is unlikely to go beyond grey-zone tactics, as Beijing’s aim is to secure acquiescence to its maritime claims. Over time, without US assistance there will be little countries like the Philippines can do to stop this, and perceptions of the US as a reliable partner will begin to erode.
When it comes to Taiwan, however effective grey-zone coercion or even an actual blockade is, if Xi is to achieve his aim of unification, PLA troops will at some point need to occupy the island. If Xi believes that the Trump administration is unlikely to follow through on deterrence – and once he is confident in the PLA’s ability to prevail – he may seek to act sooner than otherwise. In such a context, increased US military sales to Taiwan – popular with Trump and members of his cabinet – could backfire by serving as justification for Chinese pre-emptive action.