US House Speaker Nancy Pelosi and members of a Congressional delegation issued a statement upon arrival in Taiwan on Tuesday.
The visit is the first official visit to Taiwan by a Speaker of the United States House of Representatives in 25 years.
"Our Congressional delegation's visit to Taiwan honours America's unwavering commitment to supporting Taiwan's vibrant Democracy.
"Our visit is part of our broader trip to the Indo-Pacific � including Singapore, Malaysia, South Korea and Japan � focused on mutual security, economic partnership and democratic governance. 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.
"Our visit is one of several Congressional delegations to Taiwan � and it in no way contradicts the longstanding United States policy, guided by the Taiwan Relations Act of 1979, US-China Joint Communiques and the Six Assurances. The United States continues to oppose unilateral efforts to change the status quo," it added.
Pelosi landed in Taiwan late on Tuesday for a visit to the self-governing island amid heightened threats from Chinese officials and multiple rounds of military drills by China's People's Liberation Army, RFA reported.
Pelosi, the most senior US official to visit Taiwan in 25 years, flew into the Songshan airport near the capital Taipei at around 10:45 p.m. local time, after leading a Congressional delegation trip reaffirming the US commitment to Asian allies.
Hundreds of Taiwanese, as well as Tibetans, gathered at her hotel to welcome the 82-year-old lawmaker, a staunch critic of Beijing for long.
In the run up to the trip, both China and Taiwan's militaries were on high-alert in preparation for the visit. Chinese domestic air travel in Fuzhou, across the Taiwan strait from Taiwan, was disrupted on Tuesday, indicating that military flights may be taking place nearby.
Taiwanese civilians have been participating in air raid drills to prepare for a potential attack by China's much larger military, RFA reported.
The United States does not recognise Taiwan diplomatically, but retains close unofficial ties with Taipei and is obligated by law to provide it with defence capabilities.
Beijing considers the self-ruling, democratic island a breakaway province, to be united with the mainland by force if necessary, and objects strongly to high-level US visits.