NEW YORK--In a highly sensitive U.S. visit, Taiwan’s president delivered the message Thursday that keeping her self-ruled island strong will help ensure the world’s safety--even as her travel is carefully calibrated to try to contain what furious Chinese officials warn could be a strong response.

Taiwan is billing President Tsai Ing-wen’s visit to New York as simply a “transit,” but she kept a full agenda of events Wednesday and Thursday before flying to Central America.

Most provocatively in the eyes of Beijing, her trip is expected to include a meeting with House Speaker Kevin McCarthy next week. In a sign of the sensitivity of her visit, little about Tsai’s full itinerary has been made public, and her events Thursday were closed to the news media.

The visit--while important for Taiwan in demonstrating its overseas support--is fraught for both Taiwan and the U.S. because China views Taiwan as its territory and treats any dealings between U.S. and Taiwanese officials as a challenge to its sovereignty.

Even with the precautions, Tsai’s trip, including any meetings with U.S. lawmakers, raises tensions at a time when both China and the U.S. and its allies are boosting their military preparedness for a possible confrontation in the Indo-Pacific. China’s often-stated determination to take Taiwan, by force if necessary, stands as one of the region’s main flashpoints.

Chinese officials are focusing, angrily, on the expected meeting next week between Tsai and McCarthy. It would be one of the highest-level in-person meetings between U.S. and Taiwanese officials on U.S. soil.

Tsai spoke on the role of Taiwan in the world’s economy and security in a closed-door speech Thursday night hosted by the Hudson Institute think tank, which awarded her its leadership award. Repeating a theme of her trip, “she made a strong point that the defense of Taiwan is actually the defense of America,” said Miles Yu, a Hudson Institute director who attended.

A few dozen pro-China demonstrators--holding signs declaring “One China” and “Taiwan is an inalienable part of China”--gathered behind police barricades outside the hotel where Tsai spoke.

The United States’ longstanding “one-China” policy acknowledges that the Chinese claim Taiwan as their territory. However, the U.S. does not endorse that claim and remains Taiwan’s most important provider of military hardware and other defense assistance.

On Thursday, Chinese Foreign Ministry spokesperson Mao Ning restated China’s serious objections to any interactions between Tsai and U.S. leaders.

“China firmly opposes any form of official interaction between the U.S. and Taiwan,” Mao told reporters in Beijing. “China will continue to closely follow the situation and resolutely safeguard our sovereignty and territorial integrity.”

A senior Chinese diplomat in Washington, embassy charge d’affaires Xu Xueyuan, pointed to the anticipated meeting between Tsai and the U.S. House speaker as one that would have significant repercussions overall and a “serious, serious, serious” impact on U.S.-China relations.

Neither Taiwan nor McCarthy, a California Republican, has publicly confirmed any in-person get-together. Analysts have framed a session between the two outside Washington as possibly less provocative than a trip by McCarthy to Taiwan, which he has said he also intends to make

Beijing responded to a visit by then-House Speaker Nancy Pelosi last August by launching missiles, deploying warships across the median line of the Taiwan Strait and simulating a blockade of the island. China also temporarily suspended dialogue with the U.S. on climate and other major issues and restricted military-to-military communication with the Pentagon.

The United States broke off official ties with Taiwan in 1979, when it formally established diplomatic relations with China. U.S. law requires Washington to treat all threats to the island as matters of “grave concern” but does not explicitly say whether the U.S. would commit troops.

Sen. Robert Menendez, a New Jersey Democrat and chairman of the Senate Foreign Relations Committee, said he hoped any U.S. officials meeting unofficially with the Taiwanese president emphasize that American support for Taiwan is “strong and unequivocal.”

Tsai has made six previous trips through the U.S. during her presidency, meeting with members of Congress and members of the Taiwanese diaspora. Administration officials are underscoring that her trip is in line with what she and her predecessors have done in the past.

Tsai’s “transit is consistent with our longstanding unofficial relationship with Taiwan and is consistent with the United States’ one-China policy, which remains unchanged,” White House national security spokesman John Kirby told reporters.

“The People’s Republic of China should not use this transit as a pretext to step up any aggressive activity around the Taiwan Strait,” Kirby said. “The United States and China have differences when it comes to Taiwan. But we have managed those differences for more than 40 years.”

Tsai told reporters before boarding her plane to the United States that “external pressure will not obstruct our resolution to engage with the world.”

Tsai was expected to meet with the American Institute in Taiwan chair, Laura Rosenberger. AIT is the U.S. government-run nonprofit that carries out unofficial relations with Taiwan.

Tsai’s stops in Central America are expected to shore up Taiwan’s partnerships there, after Honduras this month switched its diplomatic relations from Taiwan to China. Tsai accused China of using “dollar diplomacy” to lure away Honduras. Worldwide, just 13 countries now officially recognize Taiwan.

Republican Rep. Mike Gallagher of Wisconsin, the chairman of the House Select Committee on China, said the visit is a chance for Tsai “to convey to the Congress how important the partnership between the U.S. and Taiwan is and what’s necessary to preserve peace and stability across the Taiwan Strait.”

Tensions between Washington and Beijing have grown as China under President Xi Jinping seeks to expand its regional and global influence. Passage of what the U.S. said was a Chinese spy balloon across the U.S. this winter heightened Americans’ sense of challenge from China. China says it was a research balloon that was blown off course.