US House of Representatives Speaker Nancy Pelosi has arrived in Taiwan, starting a visit that Beijing had warned her against taking.
Ms Pelosi is on a tour of Asia that includes announced visits to Singapore, Malaysia, South Korea and Japan.
China claims self-ruled Taiwan as its own, and a foreign ministry spokesman said earlier this week that any visit by Ms Pelosi would be "a gross interference in China's internal affairs" and warned that "the Chinese People's Liberation Army will never sit idly by."
On arrival to Taiwan, Ms Pelosi was welcomed by a Taipei 101 skyscraper message which read: "Thank you, TW (heart image) US speaker Pelosi. Welcome to TW."
Nancy Pelosi has arrived in Taiwan JONATHAN ERNST
Ms Pelosi was welcomed as she arrived in Taiwan ANN WANG
Ms Pelosi's trip to Taiwan capped her decades as a leading US critic of the Beijing government, especially on rights issues, and underscores the long history of the US Congress taking a harder line than the White House in dealings with Beijing.
Second in line for the presidency after Vice President Kamala Harris, Pelosi became the most senior US politician to travel to Taiwan since then-Speaker Newt Gingrich in 1997. She led a delegation of six other House members.
As Ms Pelosi touched down, Chinese fighter jets were spotted crossing the Taiwan Straits, according to local media.
While China's foreign ministry condemned Ms Pelosi's visit, saying it seriously damages peace and stability in the Taiwan Strait.
In a statement issued just after her arrival in Taipei late on Tuesday, China's foreign ministry said Pelosi's visit severely impacts the political foundations of China-US relations, and said it had lodged a strong protest with the US.
Speaking on Twitter, Ms Pelosi wrote: "Our delegation’s visit to Taiwan honours America’s unwavering commitment to supporting Taiwan’s vibrant Democracy.
“Our discussions with Taiwan leadership reaffirm our support for our partner & promote our shared interests, including advancing a free & open Indo-Pacific region."
"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."
"Our visit is one of several Congressional delegations to Taiwan – and it in no way contradicts longstanding United States policy, guided by the Taiwan Relations Act of 1979, U.S.-China Joint Communiques and the Six Assurances."