Taiwanese President Tsai Ing-wen arrived in the United States on Thursday on a trip that has angered Beijing, warning that democracy must be defended and that the island faced threats from "overseas forces," in a veiled reference to China.

China, which claims self-ruled and democratic Taiwan as its own and views it as a wayward province, had called on the US not to allow Tsai to transit there on her overseas tour.

"I want to reiterate that Taiwan is not, and will never, be intimidated," Tsai told a reception in New York for representatives of Taipei's 17 diplomatic allies, almost all small Central American, Caribbean or Pacific nations.

"The challenges we face only serve to strengthen our resolve to engage with the international community," she said. 

"The 23 million people of Taiwan have a right to participate in international affairs and this right should not be subject to political preconditions."

Tsai is spending four nights in the US – two on the first leg and two on the way back from a visit to four Caribbean allies. She began her trip in New York and is expected to stop in Denver on her way back.

Shortly before Tsai was due to arrive at her Manhattan hotel, a Reuters photographer witnessed a brawl at the hotel's entrance between dozens of pro-China and pro-Taiwan protesters, which was eventually broken up by police.

The New York Police Department was not immediately able to comment on whether there had been any arrests.

Tsai was last in the US in March, but her stops this time will be unusually long, as normally she spends just a night at a time in transit.

The US State Department has said there had been no change in its 'one-China' policy, under which Washington officially recognises Beijing and not Taipei, while assisting Taiwan.

However, analysts said the extended stopovers served to emphasise the Trump administration's support for Tsai at a time when she has been coming under increasing pressure from Beijing, a major US security rival with which Washington has been engaged in a year-long trade war.

Speaking before departure at Taipei's main international airport at Taoyuan, Tsai said she would share the values of freedom and transparency with Taiwan's allies, and was looking forward to finding more international space for Taiwan.

"Our democracy has not come easily and is now facing threats and infiltration from overseas forces," Tsai said, without being specific.

"These challenges are also common challenges faced by democracies all over the world," she said. 

"We will work with countries with similar ideas to ensure the stability of the democratic system."

Caribbean stops

Taiwan has been trying to shore up its diplomatic alliances amid pressure from China. Tsai will be visiting St Vincent and the Grenadines, St Lucia, St Kitts and Nevis, and Haiti on her overseas tour.

In New York, Tsai will meet with members of the Taiwanese community.

The State Department described Tsai's visit as "private and unofficial" and said she would be greeted in New York by James Moriarty, chairperson of the American Institute in Taiwan, the de facto US embassy in Taipei. 

It did not respond when asked if Tsai would have contact with any other US officials.

Seeking to bolster Taiwan's defences, the US this week approved an arms sale worth an estimated US$2.2 billion (RM9.05 billion) for Taiwan, despite Chinese criticism.

Tsai, who is up for re-election in January, has repeatedly called for international support to defend Taiwan's democracy in the face of Chinese threats. Beijing has regularly sent military aircraft and ships to circle Taiwan on drills in the past few years.

Douglas Paal, who served as US representative to Taiwan from 2002 to 2006, said Tsai's extended stopovers showed US approval for the "caution and restraint" she had shown in her dealings with Beijing.

"It makes sense to reinforce that with generous transit treatment," he said. "This is also... a message to China. The US government believes Tsai is behaving responsibly in respecting the framework of US-China-Taiwan relations."

Paal said the Trump administration had yet to indicate a significant shift in the traditional US approach to Taiwan, but this could change in the event of a deterioration of US relations with Beijing.

"It's like an engine running at a high idle," he said. 

"Trump has not engaged the gears, but there is a lot of activity at lower levels seeking to upgrade relations. 

"So change has not occurred in a big way yet, but it could happen at any time. With unpredictable consequences."

- Reuters