TOKYO (Kyodo) -- Japanese Prime Minister Sanae Takaichi said Tuesday that she reaffirmed close cooperation with the United States during a call with President Donald Trump, which came shortly after he spoke with Chinese President Xi Jinping.

Takaichi told reporters that Trump had requested the talks with her and briefed her on his phone conversation with Xi on Monday. However, she refrained from elaborating further, including on any discussion regarding her comments on a Taiwan contingency.

Japan and China have been locked in an escalating diplomatic dispute since Beijing harshly criticized Takaichi's answer to parliamentary questions on Nov. 7, in which she said a military attack on Taiwan could present a "survival-threatening situation" for Japan.

Takaichi's remarks were interpreted as indicating that her government could authorize the Self-Defense Forces to take action in support of the United States if China were to impose a maritime blockade on Taiwan or engage in other forms of coercion.

Takaichi also said she answered Trump's questions about the Group of 20 summit held in South Africa last weekend, which she attended and the U.S. government boycotted. Trump told her he welcomes phone calls from a "close friend" anytime.

Trump has not yet indicated his stance on Takaichi's comments about a Taiwan contingency. China's Foreign Ministry, however, said Trump told Xi that he understands the importance of the Taiwan issue during their talks.

Chinese Foreign Ministry spokeswoman Mao Ning said at a press conference in Beijing on Tuesday that the call between Xi and Trump was initiated at Washington's request, describing the atmosphere of the conversation as "positive, friendly and constructive."

On Tuesday, Chief Cabinet Secretary Minoru Kihara said at a regular press conference that stable U.S.-China ties are "extremely important" for Japan and the international community, but he stayed tight-lipped on Beijing's statement about the Trump-Xi talks.

Japan, based on its relationship of trust with its ally, the United States, will continue to urge China to "fulfill the responsibilities appropriate to its role," Kihara, the top Japanese government spokesman, said.

Days after Takaichi took office on Oct. 21, Trump visited Japan for in-person talks. Takaichi then met with Xi on the sidelines of the Asia-Pacific Economic Cooperation summit in South Korea late last month.

Meanwhile, Taiwan Premier Cho Jung-tai on Tuesday pushed back against Xi's remarks in the phone call with Trump that the self-ruled island's return to the mainland is "part of the postwar international order," saying the territory's 23 million people have no such option.

Cho said Taiwan plays a critical role in regional security and global technological and economic development, adding that maintaining the status quo in cross-strait relations is a shared concern of the international community.

China regards Taiwan as a renegade province to be unified with the mainland, by force if necessary. Communist-led China and the self-ruled democratic island have been governed separately since they split in 1949 due to a civil war.