US house speaker Nancy Pelosi has said she and other members of Congress visiting Taiwan are showing they will not abandon their commitment to the self-governing island.

“Today the world faces a choice between democracy and autocracy,” she said in a short speech during a meeting with Taiwan’s President Tsai Ing-wen.

“America’s determination to preserve democracy, here in Taiwan and around the world, remains ironclad.”

China, which claims Taiwan as its territory and opposes any engagement by Taiwanese officials with foreign governments, announced multiple military exercises around the island and issued a series of harsh statements after the delegation touched down in the Taiwanese capital, Taipei, on Tuesday night.

Ms Pelosi’s trip has heightened US-China tensions more than visits by other members of Congress because of her high-level position as leader of the House of Representatives. She is the first speaker of the house to come to Taiwan in 25 years, since Newt Gingrich in 1997.

Ms Tsai, thanking Ms Pelosi for her decades of support for Taiwan, presented the speaker with a civilian honour, the Order of the Propitious Clouds. She was more pointed about Chinese threats in her remarks than Ms Pelosi was.

“Facing deliberately heightened military threats, Taiwan will not back down,” Ms Tsai said. “We will firmly uphold our nation’s sovereignty and continue to hold the line of defence for democracy.”

Shortly after Ms Pelosi landed, China announced live-fire drills that would start on Tuesday night and a four-day exercise beginning on Thursday in waters on all sides of the island.

China’s air force also flew a relatively large contingent of 21 war planes, including fighter jets, toward Taiwan.

Ms Pelosi noted that support for Taiwan is bipartisan in Congress and praised the island’s democracy.

Her focus has always been the same, she said, going back to her 1991 visit to Beijing’s Tiananmen Square, when she and other lawmakers unfurled a small banner supporting democracy, two years after a bloody military crackdown on protesters at the square.

That visit was also about human rights and what she called dangerous technology transfers to “rogue countries”.

Ms Pelosi is visiting a human rights museum in Taipei later on Wednesday before she departs for South Korea, the next stop on an Asia tour that also includes Singapore, Malaysia and Japan.