Originally Published: 02 AUG 22 10:51 ET

Updated: 02 AUG 22 12:36 ET

By Jeremy Herb and Eric Cheung, CNN

(CNN) -- US House Speaker Nancy Pelosi landed in Taipei on Tuesday, marking a significant show of support for Taiwan despite China's threats of retaliation over the visit.

Pelosi's stop in Taipei is the first time that a US House speaker has visited Taiwan in 25 years. Her trip comes at a low point in US-China relations and despite warnings from the Biden administration against a stop in Taiwan.

Pelosi and the congressional delegation that accompanied her said in a statement on Tuesday that the visit "honors America's unwavering commitment to supporting Taiwan's vibrant democracy."

"Our discussions with Taiwan leadership will focus on reaffirming our support for our partner and on promoting our shared interests, including advancing a free and open Indo-Pacific region," the statement said. "America's solidarity with the 23 million people of Taiwan is more important today than ever, as the world faces a choice between autocracy and democracy."

Pelosi is traveling with House Foreign Affairs Chairman Gregory Meeks of New York, Veterans' Affairs Chairman Mark Takano of California and Reps. Suzan DelBene of Washington state, Raja Krishnamoorthi of Illinois and Andy Kim of New Jersey.

The House speaker is expected to visit Taiwan's presidential office and parliament on Wednesday morning (local time), a senior Taiwanese official told CNN. She will first visit the parliament before heading to the presidential office for a meeting with Taiwan's President Tsai Ing-wen, the official said.

Pelosi is expected to depart Taiwan later on Wednesday, according to a news release issued by the foreign ministry. The official was not authorized to speak about Pelosi's travel plans that have not been publicized.

The American Institute in Taiwan said Pelosi's delegation will meet with senior Taiwanese leaders "to discuss US-Taiwan relations, peace and security, economic growth and trade, the Covid-19 pandemic, the climate crisis, human rights, democratic governance, and other significant issues of mutual interest," the institute said in a statement.

Pelosi wrote an op-ed that published in The Washington Post after she landed Tuesday, arguing that her trip demonstrated the US commitment to Taiwan under threat from China. "In the face of the Chinese Communist Party's accelerating aggression, our congressional delegation's visit should be seen as an unequivocal statement that America stands with Taiwan, our democratic partner, as it defends itself and its freedom," the California Democrat wrote.

Pelosi's stop in Taiwan was not listed on the itinerary of her congressional visit to Asia, but the stop had been discussed for weeks in the lead up to her trip. The potential stop prompted warnings from China as well as the Biden administration, which has briefed the speaker about the risks of visiting the democratic, self-governing island, which China claims as part of its territory.

China's Ministry of Foreign Affairs released a statement after Pelosi landed, charging that her visit "has a severe impact on the political foundation of China-U.S. relations, and seriously infringes upon China's sovereignty and territorial integrity."

"It gravely undermines peace and stability across the Taiwan Strait, and sends a seriously wrong signal to the separatist forces for 'Taiwan independence,'" the foreign ministry said. "China firmly opposes and sternly condemns this, and has made serious démarche and strong protest to the United States."

The statement followed a Monday warning from China against the "egregious political impact" of Pelosi's visit, saying that the Chinese military "won't sit by idly" if Beijing believes its "sovereignty and territorial integrity" is being threatened.

The White House said Tuesday that Pelosi's trip was consistent with US policy on Taiwan, and that the US would be watching China's actions closely after Pelosi leaves.

"Obviously, we're going to be watching this closely. There is no reason for this visit to become a spurring event for a crisis or a conflict or for a pretext that the Chinese might try to whip up for some sort of military action," National Security Council coordinator for strategic communications John Kirby said on CNN's "At this Hour with Kate Bolduan" on Tuesday.

"Of course, we're concerned about that, which is why part and parcel of her trip is to reaffirm the United States commitment under the Taiwan Relations Act to help Taiwan with its self-defense," Kirby added. "Again, there's no reason for this to erupt in to conflict. There's no change to our policy. This is absolutely consistent with it. And we're just going to watch as things unfold."

White House officials had warned Beijing on Monday not to take any escalatory actions in response to Pelosi's trip. "There is no reason for Beijing to turn a potential visit, consistent with long standing US policy, into some sort of crisis or conflict, or use it as a pretext to increase aggressive military activity in or around the Taiwan Strait," Kirby told reporters on Monday.

Secretary of State Antony Blinken also said Monday that the decision to visit Taiwan was the speaker's, noting there was past precedent of members of Congress -- including previous House speakers -- visiting. "Congress is an independent, coequal branch of government," Blinken said in remarks at the United Nations. "The decision is entirely the speaker's."

A group of more than two dozen Senate Republicans, including Senate GOP Leader Mitch McConnell, issued a statement supporting Pelosi's congressional delegation, which was all Democrats, landing in Taiwan.

"We support Speaker of the House of Representatives Nancy Pelosi's trip to Taiwan," the Republicans said. "For decades, members of the United States Congress, including previous Speakers of the House, have travelled to Taiwan. This travel is consistent with the United States' One China policy to which we are committed. We are also committed now, more than ever, to all elements of the Taiwan Relations Act."

US President Joe Biden has said publicly that the US military did not believe it was a good time for Pelosi to visit Taiwan, but he stopped short of telling her directly not to go, two sources previously told CNN.

The issue of Taiwan remains among the most contentious in US-China relations. Biden and his Chinese counterpart, Xi Jinping, discussed it at length during a phone call last week that lasted more than two hours.

Administration officials are concerned that Pelosi's trip comes at a particularly tense moment, as Xi is expected to seek an unprecedented third term at the upcoming Chinese Communist Party congress. Chinese party officials are expected to begin laying the groundwork for that conference in the coming weeks, putting pressure on the leadership in Beijing to show strength.

While Biden has not endorsed Pelosi's visit, US officials believe Chinese leadership may be conflating the House speaker's trip with an official administration visit, and they're concerned that China doesn't separate Pelosi from Biden, much, if at all, since both are Democrats.

Pelosi has long been a China hawk in Congress. She's previously met with pro-democracy dissidents and the Dalai Lama -- the exiled Tibetan spiritual leader who remains a thorn in the side of the Chinese government. She also helped display a black-and-white banner in Beijing's Tiananmen Square two years after the 1989 massacre, and in recent years she's voiced support for the pro-democracy protests in Hong Kong.

This story has been updated with additional developments.