Japan is calling on the United States to bolster its public support for Prime Minister Sanae Takaichi, following comments she made about Taiwan that have provoked a strong reaction from China. Tokyo is reportedly dissatisfied with the current level of backing from Washington, as tensions rise over Takaichi’s remarks suggesting that a Chinese attack on Taiwan could pose an “existential threat” warranting Japan’s military involvement.

Sources familiar with diplomatic conversations have indicated that Shigeo Yamada, Japan’s ambassador to the U.S., has approached the Trump administration seeking a more robust display of support for Tokyo. This request comes amid a backdrop of Chinese outrage, which has included threats of economic retaliation and warnings to Chinese citizens to steer clear of Japan.

The situation escalated over the weekend when Takaichi reported an incident involving Chinese warplanes targeting Japanese fighter jets with radar near Okinawa. She condemned the event as “extremely regrettable,” asserting Japan’s strong protest to China and a firm demand for preventative measures against future occurrences. “We will respond calmly and resolutely,” Takaichi assured reporters, as reported by Kyodo.

While there has been some expression of support from the U.S., such as George Glass, the ambassador to Japan, affirming that President Trump and his team “have her back,” the Japanese government feels that more public affirmations are necessary. The call for increased support underscores the delicate balance in international relations as Japan navigates its position between a rising China and its long-standing alliance with the United States.

“Japan has strongly protested to the Chinese side, and we firmly requested measures to prevent recurrence,” she told reporters on Sunday, according to Kyodo. “We will respond calmly and resolutely.”

Washington has offered some support to Takaichi with George Glass, ambassador to Japan, last month telling reporters Trump and his team “have her back”. But there has been little other direct public support.

The crisis in Japan-China relations comes as Trump has told his team not to take actions that could jeopardise the trade deal he reached with Chinese President Xi Jinping in October.

One Japanese official said Tokyo did not believe the US was wavering in its commitment to Japan, but added that there was deep disappointment at the lack of public support from top officials in Washington.

Christopher Johnstone, a former top White House Japan official, said Washington should have welcomed Takaichi’s declaration that Japan would help US forces if they were attacked while defending Taiwan from China.

“This was the clearest statement ever made by a Japanese prime minister about Japan’s obligations to the US during a Taiwan contingency,” said Johnstone, now at The Asia Group consultancy.

“Setting aside whether it was wise to make that statement publicly, it was one that Washington should have embraced. Instead, with the exception of messages from the US embassy in Tokyo, it has been met largely with silence.”

Some people said the lack of US support was ironic given that Elbridge Colby, the under-secretary of defence for policy, had pushed Japan to make clear what role it would play if the US and China went to war over Taiwan.

After earlier requests for support, US officials told Tokyo a strong statement would come from Washington, but Japan was disappointed when that appeared to be a social media post on X from the state department’s deputy spokesperson, according to people familiar with the situation.

This week, Chris Landau, deputy secretary of state, spoke to Takehiro Funakoshi, head of the Japanese foreign ministry. The state department said he reaffirmed the US commitment to the alliance, but the call readout did not mention the aggressive Chinese response to Takaichi’s statement.

Trump has not offered any public support for Takaichi despite the warm relationship they established in Tokyo in October. Asked about the Japanese request for more support, the White House noted that Trump had described his relationship with Takaichi as “great”. The state department pointed to the X post from the spokesperson.

“The absence of public statements of support for Prime Minister Sanae Takaichi from both the White House and the Department of State is perplexing and must be unnerving for both Tokyo and Taipei,” said Dennis Wilder, former top Asia adviser in the George W Bush White House.

In an interview with Fox News last month, Trump was asked about a social media post from the Chinese consul-general in Osaka who suggested that Takaichi should be killed over her comments.

If a “filthy neck sticks itself in uninvited, we will cut it off without a moment’s hesitation”, he wrote in a since deleted post.

Trump replied: “A lot of our allies aren’t our friend.” He did not offer any support for Takaichi even though her mentor Shinzo Abe, the former prime minister who was close to Trump, was assassinated in 2022.

Randy Schriver, chair of the Institute for Indo-Pacific Security and the Pentagon’s top Asia official in Trump’s first term, said it would have been “appropriate” for the White House to issue a strong defence of Takaichi.

Speaking at Georgetown University this week, he added that there should also have been more pushback over the consul-general’s comment. “Threatening her life when her mentor was assassinated . . . is outrageous.”

The Wall Street Journal last month reported Trump had urged Takaichi not to provoke China over Taiwan in a call that came later on a day when he had also spoken to Xi. The Japanese government denied the report.

Several people in Washington and Tokyo familiar with the call said Trump told the Japanese leader it would be preferable for tensions not to escalate but did not tell her not to provoke China or avoid particular actions.

“Japan is America’s indispensable ally in the Indo-Pacific,” said Nicholas Burns, the US ambassador to China under Joe Biden. “Prime Minister Takaichi deserves our full public support in response to Beijing’s cynical attempt to intimidate her and to weaken the US-Japan alliance.”

The Japanese embassy in Washington declined to comment.