China vowed reprisals against Taiwan after a meeting between the United States House speaker and the island’s president, saying Thursday that the U.S. was on a “wrong and dangerous road.”

Speaker Kevin McCarthy hosted Taiwan President Tsai Ing-wen on Wednesday in a show of U.S. support for the self-ruled island, which China claims as its own, along with a bipartisan delegation of more than a dozen U.S. lawmakers.

The Biden administration maintains there is nothing provocative about the visit by Tsai, which is the latest of a half-dozen to the U.S. Yet, it comes as the U.S.-China relationship has fallen to historic lows, with U.S. support for Taiwan becoming one of the main points of difference between the two powers.

But the formal trappings of the meeting, and the senior rank of some of the elected officials in the delegation from Congress, could lead China to view it as an escalation. No speaker is known to have met with a Taiwan president on U.S. soil since the U.S. broke off formal diplomatic relations in 1979.

In response to the meeting, Beijing said it would take “resolute and forceful measures to defend national sovereignty and territorial integrity,” in a statement issued early Thursday morning by the Ministry of Foreign Affairs.

It urged the U.S. “not to walk further down a wrong and dangerous road.”

In December, China’s military sent 71 planes and seven ships toward Taiwan in a 24-hour display of force directed at the self-ruled island after China expressed anger at Taiwan-related provisions in a U.S. annual defense spending bill. China’s military pressure campaign on Taiwan has intensified in recent years, and the Communist Party has sent planes or ships toward the island on a near-daily basis.

But as of Thursday afternoon, there was no overt sign of a large-scale military response.

“We will take resolute measures to punish the ‘Taiwan independence’ separatist forces and their actions, and resolutely safeguard our country’s sovereignty and territorial integrity,” said a statement from China’s Taiwan Affairs Office Thursday morning, referring to Tsai and her political party as separatists.

Chinese vessels were engaged in a joint patrol and inspection operation in the Taiwan Strait that will last three days, state media said Thursday morning. The Fujian Maritime Safety Administration said its ship, the Haixun 06, would inspect cargo ships and others in the waters that run between Taiwan and China as part of the operation.

Taiwan’s Ministry of National Defense said Wednesday evening it had tracked China’s Shandong aircraft carrier passing southeast of Taiwan through the Bashi Strait. On Thursday morning, it tracked three People’s Liberation Army navy vessels and one warplane in the area around the island.

‘Resolute’ American Support

U.S. Congressional visits to Taiwan have stepped up in frequency in the past year, and the American Institute in Taipei, the de facto embassy, announced the arrival of another delegation Thursday. House Foreign Affairs Committee head Michael McCaul of Texas is leading a delegation of eight other lawmakers for a three-day visit to discuss regional security and trade, according to a statement from AIT.

At their meeting Wednesday, Tsai and McCarthy spoke carefully to avoid unnecessarily escalating tensions with Beijing. Standing side by side at the Ronald Reagan Presidential Library in California, the two acknowledged China’s threats against the island government.

“America’s support for the people of Taiwan will remain resolute, unwavering and bipartisan,” McCarthy said at a news conference later. He also said U.S.-Taiwan ties are stronger than at any other point in his life.

Tsai said the “unwavering support reassures the people of Taiwan that we are not isolated.”

More than a dozen Democratic and Republican lawmakers, including the House’s third-ranking Democrat, had joined the meeting.

Tsai said she and McCarthy spoke of the importance of Taiwan’s self-defense, of fostering robust trade and economic ties and supporting the island government’s ability to participate in the international community.

But she also warned, “It is no secret that today the peace that we have maintained and the democracy which we have worked hard to build are facing unprecedented challenges.”

“We once again find ourselves in a world where democracy is under threat and the urgency of keeping the beacon of freedom shining cannot be understated,” she said.

The United States broke off official ties with Taiwan in 1979 while formally establishing diplomatic relations with the Beijing government. As part of its recognition of China, the U.S. “One China” policy acknowledges that Beijing lays claim to Taiwan, but does not endorse China’s claim, and the U.S. remains Taiwan’s key provider of military and defense assistance.

Washington also has a policy of strategic ambiguity, where it does not explicitly say whether it will come to Taiwan’s aid in the case of a conflict with China.

In Taiwan, Tsai’s visit did not make a huge splash, though fellow politicians paid close attention.

Ko Wen-je, the former Taipei city mayor who’s thought to have presidential aspirations, said he welcomed any exchange between Taiwan and international leaders.

“Taiwan hopes to have a greater space to operate globally, and the mainland shouldn’t get flustered because of this,” Ko wrote on his Facebook page. “It should show the attitude of a civilized nation and stop its suppression by military force.”

Opposition lawmaker Johnny Chiang of the Nationalist party said that Tsai’s meeting with McCarthy was still within the guardrails of the “One China” policy because it showed that while Congress was relatively free to support Taiwan, the White House was more constrained, according to local media.

In August, then-House Speaker Nancy Pelosi traveled to Taiwan to meet with Tsai. China responded with its largest live-fire drills in decades, including firing a missile over the island.

Taiwan and China split in 1949 after a civil war and have no official relations, although they are linked by billions of dollars in trade and investment.