Nancy Pelosi landed in Taiwan on Tuesday night in the highest-level visit by a US official for decades, defying Chinese threats of a military response.

The trip by the Speaker of the US House of Representatives has become a test of how far Beijing will go to deter foreign support for Taiwan and of China and the US’s ability to crisis-manage their increasingly tense relationship.

Shortly after landing in Taipei, Pelosi released a statement saying her visit “honours America’s unwavering commitment to supporting Taiwan’s vibrant democracy . . . as the world faces a choice between autocracy and democracy”.

The Chinese foreign ministry said Pelosi’s visit “seriously infringes China’s sovereignty and territorial integrity” and would have “a severe impact” on US-China relations.

Pelosi is the most senior US official to visit Taiwan while in office since Newt Gingrich, one of her predecessors as Speaker, did so in 1997. Beijing claims Taiwan as part of its sovereign territory and has persistently warned that the People’s Liberation Army (PLA) would “not sit by idly” if Pelosi dared visit.

In advance of Pelosi’s touchdown on Tuesday, the PLA staged air and sea manoeuvres in the South China Sea and the Taiwan Strait as well as a string of military drills in other coastal areas.

The US air force plane carrying Pelosi and her delegation did not fly directly from her previous stop of Kuala Lumpur to Taipei, taking a wide detour via Borneo and the Philippines.

Meia Nouwens, an expert on the PLA at the International Institute for Strategic Studies think-tank, said the US military might have steered clear of the skies over the South China Sea — which China claims and has increasingly militarised — because the PLA has started deploying missiles on artificial islands that could pose a risk to the aircraft.

Hours before Pelosi arrived, Chinese foreign minister Wang Yi accused the US of stirring up trouble and “hollowing out” its “one China” policy, under which it acknowledges Beijing’s view that Taiwan is part of China.

While China has threatened to invade if Taipei indefinitely refuses to submit under its control, some military experts argue Beijing’s military posturing seeks to discourage US-Taiwan engagement rather than being related to imminent invasion plans. They maintain China and the US are determined to avoid an escalation.

Pelosi flew to Taiwan over the objections of the White House, which maintained her visit would unnecessarily raise tensions with Beijing that are already extremely high.

In public, White House officials stress that Pelosi has the right to decide her own travel, since Congress is an independent branch of the US government. But President Joe Biden had dispatched several top officials, including national security adviser Jake Sullivan, in recent weeks to try to convince her not to travel to Taiwan by laying out the risks of a potential visit.

Biden also recently said the US military did not think the visit was a good idea, although defence officials have said General Mark Milley, chairman of the joint chiefs, only laid out the scenarios that could emerge surrounding her visit and the risks that her trip would entail.

Ahead of her landing in Taipei, secretary of state Antony Blinken on Monday warned China not to engage in any escalatory activity in response to Pelosi’s visit.

The White House said there were signs that China was preparing a military response that could include firing missiles into the Taiwan Strait for the first time since the last big Taiwan crisis in 1995-96.

But despite earlier suggestions by analysts that Pelosi could keep the stop brief and low-key to avoid inflaming tension with China further, she is spending the night and a full programme has been lined up for her on Wednesday.

In the morning, Pelosi will visit Taiwan’s parliament and then meet with President Tsai Ing-wen, followed by lunch at the Taipei Guesthouse, the Japanese colonial-era mansion where the foreign ministry treats visiting dignitaries, and a visit to a human rights memorial.

That would give her visit a higher profile than that of Gingrich, who stayed only a few hours 25 years ago.

“The Chinese always seek to undermine precedent, but we need to push back and defend precedent in order not to have our international space squeezed further,” said Vincent Chao, a former assistant to foreign minister Joseph Wu and former head of the political section at Taiwan’s representative office in Washington.

The Taiwanese government has been torn between concerns about Chinese military aggression and worry that cancelling Pelosi’s visit under Chinese pressure would strengthen Beijing’s quest to coerce Taiwan into unification. “This has put us in a very awkward position,” said a senior official.

But Pelosi’s insistence on the trip has buoyed many Taiwanese.

“No one has the right to say whether Speaker Pelosi ‘should’ come to Taiwan or not. Only she can decide, and she should not feel threatened,” tweeted Kolas Yotaka, a former presidential office spokesperson who is running for office in local elections later this year.

“I am looking forward to her visit. It makes us feel less isolated, and believe there are still people who maintain their beliefs and ideals.”