"Call me anytime" was the message Japanese Prime Minister Sanae Takaichi said she received from U.S. President Donald Trump on Tuesday in their first phone call since Tokyo's leader sparked a major diplomatic bust-up with China.

Takaichi's off-the-cuff remark in parliament earlier this month that a hypothetical Chinese attack on Taiwan could trigger Japanese military action prompted a furious response from Beijing that has included a boycott on travel to Japan.

China claims Taiwan as its own and has not ruled out using force to take control of it. Taiwan sits just more than 100 km (60 miles) from Japanese territory.

However, the island's government rejects Beijing's claim and says only Taiwan's people can decide their future.

Trump has not commented publicly on the dispute between Japan - a key U.S. security ally - and rival superpower China, a silence that analysts say will be concerning to some officials in Tokyo.

In brief remarks following Takaichi's call with Trump, she sought to dispel any concerns that the U.S. president did not have her back.

"President Trump mentioned that he and I are extremely good friends, and that I should call him anytime," Takaichi told reporters, adding that it was Trump who took the initiative to reach out to her.

Trump explained to Takaichi the recent state of U.S.-China relations including his phone call with Chinese President Xi Jinping on Monday, she added.

Xi told Trump in that call that Taiwan's "return to China" is a key part of Beijing's vision for the world order, China's official Xinhua news agency reported.

Trump touted progress in trade talks and said relations with China were "extremely strong" in a post on Truth Social following his call with Xi. He made no mention of any discussions on Taiwan, however.

Japan was relieved that Trump arranged the call so soon after his discussion with Xi, said a government official with knowledge of the talks, requesting anonymity due to the sensitivity of the issue.

The White House did not immediately respond to a request for comment about Trump's call with Takaichi.

Taiwan’s Premier Cho Jung-tai responded on Tuesday, saying that “a return to China is not an option” for the island’s population.

Japan’s Chief Cabinet Secretary Minoru Kihara, asked about Xi’s reported comments, said he would not discuss the content of the leaders’ call but noted that “the stability of U.S.-China relations is extremely important for the international community, including Japan.”

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