WASHINGTON (NewsNation) — Two American warships sailed through the Taiwan Strait for the first time since House Speaker Nancy Pelosi’s visit to Taiwan sparked anger from China.

The U.S. Navy confirmed Sunday that two cruisers, the USS Chancellorsville and the USS Antietam, carried out the operation in international waters. Such operations usually take eight to 12 hours to complete and are closely monitored by China’s military.

Pelosi’s visit to Taiwan prompted China to launch a series of military exercises, including live-fire drills near the island nation. The Navy said it was a routine transit for its ships, and the Chinese government said in response it is on high alert.

The operation demonstrates the United States’ commitment to a free and open Indo-Pacific, and the U.S. military flies, sails, and operates anywhere international law allows, the Navy said.

John Kirby, a spokesperson for the U.S. National Security Council, echoed that position on CNN, saying the ships’ passage was “very consistent” with the “one-China” policy and of seeking “a free and open Indo-Pacific.”

Kirby added that the operation was planned long ago.

Multiple congressional delegations, including one with Rep. Don Beyer, have visited Taiwan after Pelosi’s trip.

“The purpose of our visit was to point out to China, if they do it in a military way, if they do something as silly as invade, there will be enormous consequences,” Beyer said. “All you have to do is look at the way the world has reacted to Russia’s invasion of Ukraine, and say the financial consequences, the economic consequences for the (People’s Republic of China) would be very unhealthy.”

Beyer said he doesn’t believe the U.S. and China are in a “cold war” situation.

The operation demonstrates the United States’ commitment to a free and open Indo-Pacific, and the U.S. military flies, sails and operates anywhere international law allows, the Navy said.

John Kirby, a spokesperson for the U.S. National Security Council, echoed that position on CNN, saying the ships’ passage was “very consistent” with the “one-China” policy and of seeking “a free and open Indo-Pacific.”

Kirby added that the operation was planned long ago.

The Chinese military’s Eastern Theater Command said it was following the ships and warning them.

“Troops in the theater remain on high alert and are ready to thwart any provocation at any time,” it added in a statement.

Taiwan’s defense ministry said the ships were sailing in a southerly direction and that its forces were observing but that “the situation was as normal”.

The narrow Taiwan Strait has been a frequent source of military tension since the defeated Republic of China government fled to Taiwan in 1949 after losing a civil war with the communists, who established the People’s Republic of China.

Reuters contributed to this report.