Donald Trump has endorsed Japan's Prime Minister Sanae Takaichi ahead of a snap election in her country on Sunday.

Takaichi has "already proven to be a strong, powerful, and wise leader... one that truly loves her country," the US president wrote in a Truth Social post on Thursday, adding: "She will not let the people of Japan down!"

While it is rare for US presidents to publicly back candidates in foreign elections, Trump has done so before, endorsing Argentina's Javier Milei and Hungary's Viktor Orban most recently.

Takaichi has courted the US president as Tokyo seeks more stability in its relationship with Washington, its closest ally, in the wake of Trump's tariffs.

Trump had threatened a 25% tariff initially, but Japan then struck a deal in July to invest $550bn (£407bn) in the US. In exchange, Washington lowered import levies to 15%.

Takaichi, 64, became PM in October after she won the leadership race in her party and secured enough support in parliament. But she called for an last month election to seek a public mandate.

Just one week after she took office, Tokyo rolled out the red carpet for Trump, deploying a full military guard of honour and band to welcome him at the Akasaka Palace, the government's state guesthouse.

It was her diplomatic debut, and the optics were striking: Takaichi aboard the aircraft carrier USS George Washington, fists pumping as the US president praised her in front of thousands of US soldiers, the images then broadcast around the world.

She sought to portray herself as a leader Trump can and wants to do business with and, perhaps more importantly for the president, someone he gets along with personally.

The two leaders also see eye-to-eye on defence. Trump wants Tokyo to spend more on its own security and so does Takaichi, as sentiment grows in Japan that it must invest more in defence.

They heaped compliments on each other during the visit and signed a deal on rare earths, as well as a document heralding a new "golden age" of US-Japan relations. Takaichi described Trump as a "partner in a new golden era", and praised his role in bringing peace to the Middle East.

"In my visit to Japan, I and all of my representatives, were extremely impressed with her," Trump wrote in his Truth Social post on Thursday, noting that the two countries have made progress in national security cooperation and on the economic front.

His post, which signals that Takaichi is a leader his administration would work with, is a message aimed not only at Japanese voters but also the region, and especially China.

Beijing and Tokyo are in the middle of a diplomatic rift, and the historically tense relationship has hit its lowest point in more than a decade.

Takaichi found herself the target of China's ire in November, when she made comments suggesting that Japan could respond with its own self-defence force if China attacked Taiwan, the self-governed island it has long claimed. She has since refused to retract the statement.

Trump's endorsement of her comes as tensions between them continue, and a day after he had a phone call with China's leader Xi Jinping.

He said he had an "extremely good" relationship with China, and that both he and Xi "realise how important it is to keep it that way".

Xi called Taiwan "the most important issue" in their relationship, emphasising that Taiwan was "China's territory", Chinese state media reported. He also told Trump that Washington should be "prudent" when supplying weapons to the self-governed island which China has long claimed.

Polls so far are predicting a landslide for Takaichi but winning Sunday's election will just be the first of several hurdles.

Her leadership will be defined by how she manages Japan's stagnant economy and the delicate relationship with the US, its most critical security ally, as well as China, its largest trading partner.