The top American diplomat for Asia has vowed that the U.S. military will continue to operate in the Taiwan Strait, saying Thursday that any moves by China to prevent the operations would be “deeply destabilizing,” just a day after Beijing’s ambassador to Washington warned against such operations.

“The White House and the Pentagon have made clear that the United States will continue to fly, sail and operate anywhere that international law allows — and that includes our continuance of routine transits through the Taiwan Strait,” said Daniel Kritenbrink, the U.S. assistant secretary of state for the Bureau of East Asian and Pacific Affairs.

“Our transits through the strait are routine and long-standing and they will continue,” he told reporters. “It would be deeply destabilizing and irresponsible if China were to try to take steps designed to control or restrict the ability of the United States or others to transit the strait, or were it to take steps that would threaten the ability of shipping and commerce to go through the strait.”

Kritenbrink’s remarks backstopped those last week by the White House’s Indo-Pacific coordinator, Kurt Campbell, who said the U.S. will conduct “freedom of navigation” exercises in the strait in the coming weeks.

China’s ambassador to Washington, Qin Gang, said earlier this week that Beijing viewed the U.S. transits of the strait as an escalation by the American side and an effort to support what he called the “separatist” government in Taiwan.

“We have noted what the U.S. military has said about the U.S. military exercises and navigation (in the Taiwan Strait), but I call on the U.S. to refrain and exercise restraint and not do anything to escalate tensions,” Qin was quoted as saying. “If there are any moves to violate China’s territorial integrity, China will respond.”

It was not clear what such a response would entail, but the Chinese military has tailed and monitored previous sailings through the strait by the U.S. Navy. Chinese military officials in recent months began asserting that the waterway is not international waters during meetings with U.S. counterparts, according to media reports. This new talking point stoked questions about whether Beijing could more actively confront U.S. and allied naval vessels in the strait.

The Taiwan Strait is a key trade artery that has seen almost half of the global container fleet and 88% of the world’s largest ships by tonnage pass through it this year, according to data compiled by Bloomberg. It is also the primary route for ships sailing from China, Japan, South Korea and Taiwan to markets in Europe, the U.S. and all stops in between — a point that Kritenbrink emphasized.

“This issue is not about bilateral U.S.-China dynamics,” Kritenbrink said. "It’s not about being asked to choose between Washington and Beijing.”

The U.S. diplomat added that while Beijing’s “growing coercion” against Taiwan risks miscalculation, maintaining peace and stability across the strait “is not just a U.S. interest, rather it is a matter of international concern critical for regional and global security and prosperity.”

U.S. officials have said that the administration of U.S. President Joe Biden is working with allies and like-minded partners to help tamp down the acrimony over Taiwan. But Kritenbrink said the White House fully expected China’s “intensified pressure campaign” against Taipei to continue to unfold “in the coming weeks and months.”

“China is increasingly willing to take irresponsible and destabilizing steps that we believe undermine” regional peace and stability, he said.

The Sino-U.S. rivalry has heated up in the wake of China’s large-scale military exercises around Taiwan earlier this month in response to a visit to the self-ruled island by U.S. House Speaker Nancy Pelosi. Those exercises included missile launches that overflew the island and landed in waters near Japan’s far-flung southwestern islands.

China considers democratically ruled Taiwan to be one of its unassailable “core interests” that must be brought back into the fold, by force if necessary. Washington, on the other hand, officially recognizes Beijing rather than Taipei under its long-standing “One China” policy, though the U.S. is also bound by the Taiwan Relations Act to provide the island with the means to defend itself. China has cited Pelosi’s trip as evidence of what it calls the "hollowing out" of this policy.

Some experts have said the Chinese exercises — which were characterized by Japan as an “intentional” show of force by Beijing — were intended to serve as a check on both Washington and Tokyo from defending Taipei in the event of a conflict.