Photographer: Tomohiro Ohsumi/Bloomberg

China warned the U.S. against disrupting relations after the U.S. Congress sent President Donald Trump legislation seeking greater diplomatic exchanges with Taiwan.

The Senate on Wednesday unanimously passed a bill encouraging visits between the U.S. and Taiwan “at all levels,” specifically citing “cabinet-level national security officials.” Such exchanges would effectively raise the diplomatic status of the democratically run island, which U.S. officials have avoided since recognizing the government in Beijing under the “one-China” policy in 1979.

Foreign Ministry spokeswoman Hua Chunying said China was “extremely dissatisfied” with the legislation, which “seriously contravenes” the understanding between the two countries.

“We have lodged solemn representations with the U.S.,” she told a regular briefing Thursday in Beijing. “The one-China principle is the political foundation for U.S.-China relations. We urge the U.S. to honor its commitment on Taiwan-related issues.”

The bill, which passed the House in January, needs only Trump’s signature to become law. Although the U.S. has often played down its military aid and unofficial diplomatic support for Taiwan over the years, the Trump administration has taken a more confrontation tone toward China over trade and was expected to announce steep tariffs on steel and aluminum Thursday that would make the country’s exports more expensive.

China and Taiwan have been ruled separately since Chiang Kai-shek’s Nationalist government fled to Taipei in 1949, and the Communist Party regards the island as a province to be taken by force if necessary. Efforts to improve ties between the sides soured in 2016, after Tsai Ing-wen, the leader of the pro-independence Democratic Progressive Party, was elected president.

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“China has made a concerted effort to isolate the people of Taiwan, and only U.S. leadership can push back against this aggression,” Senator Tom Cotton, an Arkansas Republican, said after the bill’s passage. “Now, the administration should act on it by sending senior U.S. officials to meet with their Taiwanese counterparts.”

The U.S. provides military support to the island under the Taiwan Relations Act of 1979, and Congress in September authorized naval visits with Taiwan as part of a defense spending measure. In December, a senior Chinese diplomat in Washington said that China would “unify” Taiwan by military force if a U.S. warship visited under a defense authorization approved last year.

Tsai took to Twitter to praise the bill, saying it “symbolizes the #US Congress’ longstanding support for #Taiwan.” “The Taiwan-US partnership is a key pillar of peace & stability for the Indo-Pacific region,” she said.

— With assistance by Adela Lin, and Peter Martin