Taiwan President Tsai Ing-wen left on Wednesday for a trip to Central America that will transit through the United States, sparking more tension between Beijing and Washington.

Tsai is expected to transit through New York on March 30 and Los Angeles on April 5 as part of her trip to Guatemala and Belize, returning to Taipei on April 7. On her way back, Tsai is scheduled to meet US House Speaker Kevin McCarthy, a plan that has drawn China's anger.

The Taiwanese president has transited via the United States seven times since taking office in 2016, often meeting US officials, including members of Congress. However, this will be the first meeting between a House speaker and a Taiwanese president on US soil.

Tsai's meeting with McCarthy comes at a time when relations between US and China are arguably the worst since 1979 when Washington normalized ties with Beijing and switched diplomatic recognition from Taipei. The US does not officially recognize Taiwan as an independent territory but maintains unofficial relations with the island.

China claims Taiwan as its own territory and responded adversely to a visit from then-House Speaker Nancy Pelosi in August 2022. Washington-Beijing relations have only worsened since.

Before leaving for her trip, Tsai told reporters that external pressure would not stop their determination to go out into the world.

"We are calm and confident, will neither yield nor provoke," she said at Taiwan's main international airport at Taoyuan. "Taiwan will firmly walk on the road of freedom and democracy and go into the world. Although this road is rough, Taiwan is not alone."

US and Chinese reactions to Tsai's trips

China has reacted strongly to the impending meeting in the US and threatened "to resolutely fight back."

"If she contacts US House Speaker McCarthy, it will be another provocation that seriously violates the one-China principle, harms China's sovereignty and territorial integrity and destroys peace and stability in the Taiwan Strait," Zhu Fenglian, spokesperson of China's Taiwan Affairs Office, said in a news conference. "We firmly oppose this and will definitely take measures to resolutely fight back."

This is not the first time China has threatened action over US-Taiwan ties.

The United States, meanwhile, said China has no reason to react since the planned transit was consistent with long-standing practice and the US one-China policy.

"There's absolutely no reason for Beijing to use this upcoming transit as an excuse or a pretext to carry out aggressive or coercive activities aimed at Taiwan," a senior US official said. Beijing's military, economic and diplomatic pressure on Taiwan will not alter Washington's practice of facilitating transits, he said.

A second US official, on the condition of anonymity, urged China to keep communication channels open with the US. He noted that US President Joe Biden had planned to talk to Chinese President Xi Jinping to clear the air after a US fighter jet shot down a suspected Chinese spy balloon. That talk is yet to happen. Washington and Beijing had also discussed a postponed visit by Secretary of State Antony Blinken and visits by US Treasury Secretary Janet Yellen and Commerce Secretary Gina Raimondo, he said.