Donald Trump has thrown his weight behind Japan’s prime minister, Sanae Takaichi, two days before voters go to the polls in a snap election that will test her authority at home and her strategy abroad.

The US president’s intervention is unusual in Japanese politics and rarer still in American diplomacy, where public endorsements in foreign elections are typically avoided the BBC reports. Yet Trump has shown a willingness to bend that convention, most recently offering support to leaders in Argentina and Hungary whose politics mirror his own instincts.

The endorsement lands at a delicate moment for Japan. Takaichi, who took office in October after winning her party’s leadership contest and securing parliamentary backing, dissolved the lower house last month to seek a clearer mandate from voters. The move was a calculated gamble even though opinion polls suggest she is on course for a comfortable victory, but it also exposes her to scrutiny over an economy that has struggled to regain momentum and a region growing more unstable by the week.

According to the BBC, for Washington, the timing is no accident. Japan is America’s closest ally in Asia, although this is a claim South Korea would contest, and relations have required careful management since Trump returned to office and revived his fondness for tariffs. Early threats of a 25% levy on Japanese imports rattled markets and policymakers in Tokyo. The two sides eventually struck a deal in July under which Japan pledged to invest $550bn in the US, prompting Washington to cut the tariff rate to 15%. At the time, the agreement eased immediate pressure but underlined how transactional the relationship can be.

In the months since becoming PM, Takaichi has worked hard to cultivate Trump personally as a way of stabilising that bond. Within days of taking office, she hosted him in Tokyo with full ceremonial honours, a show of warmth designed as much for domestic audiences as for the White House.

Substance has followed symbolism with defence a clear area of alignment. Trump has long argued that allies should shoulder more of their own security costs, and Takaichi has echoed that call at home, arguing Japan must invest more heavily in its armed forces as threats from China and North Korea intensify. The two governments have also moved closer on economic security, signing agreements on rare earths and supply chains as part of a broader push to reduce reliance on China.

That backdrop gives Trump’s backing a significance that extends beyond Japan’s domestic contest. It signals to the region - and particularly to Beijing just a day after Trump spoke with President Xi – that Washington and the US sees Takaichi as a dependable partner. Also in Takaichi’s time as Japanese PM, relations between China and Japan have deteriorated sharply, hitting their lowest point in more than a decade amid disputes over security and Taiwan. Takaichi has also drawn Beijing’s ire by suggesting Japan could respond militarily if China attacked the island, a stance she has refused to soften.