House Speaker Nancy Pelosi's visit to Taiwan this week is a significant moment in her long career of advocating for democracy and human rights in Asia while pressuring China and its government in Beijing.
Second in line to the presidency after Vice President Kamala Harris, Pelosi is the highest-ranking American official to visit Taiwan in 25 years, since then-Speaker Newt Gingrich's 1997 visit to the island.
The Biden administration, which appeared to have unsuccessfully attempted to dissuade Pelosi from visiting Taiwan on her trip to Asia, -- although it wouldn't confirm or deny whether it tried to so -- has warned that Beijing could retaliate economically or militarily to her visit.
"If the speaker does decide to visit and China tries to create some kind of crisis or otherwise escalate tensions, that would be entirely on Beijing," Secretary of State Antony Blinken said Monday. "We are looking for them, in the event she decides to visit, to act responsibly and not to engage in any escalation going forward."
The visit has infuriated China, which considers Taiwan a breakaway province, and has claimed sovereignty over the island. A Chinese Foreign Ministry spokesperson vowed that China would "take resolute and vigorous countermeasures" in response to Pelosi's visit.
"Everything is stormy," Derek Grossman, a senior defense analyst at the RAND Corporation, told ABC News. "And from China's perspective, they see this as yet another example of how the U.S. will not stop pushing Taiwan to think and act for itself, which is exactly what they don't want."
While the Biden administration has maintained the longstanding 'One China' policy and does not recognize Taiwanese independence -- the standoff over Pelosi's visit is also due to her reputation as a China critic and hawk, experts told ABC News.
"The Chinese just see her as rabidly anti-China, and believe that no good can come out of her," Bonnie Glaser, the director of the Asia Program at the German Marshall Fund of the United States, told ABC News.
As she landed, Pelosi and others in the congressional delegation traveling with her put out a statement saying, "Our Congressional delegation's visit to Taiwan honors America's unwavering commitment to supporting Taiwan's vibrant Democracy."
The statement continued, "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. The United States continues to oppose unilateral efforts to change the status quo."
Tiananmen Square and protecting Chinese students
Pelosi seized on human rights in China quickly after winning her first full term in Congress -- a liberal who often found common cause with conservatives on human rights issues and China after the Tiananmen Square demonstrations and violent crackdowns against protests in 1989.
Representing one of the largest Asian-American communities in the country, she was the chief sponsor of legislation that would allow thousands of Chinese students to remain in the United States after their visas expired and avoid potential persecution if they returned to China.
Despite her relatively junior status in the House, she helped propel the legislation through Congress, prompting a showdown President George H. W. Bush, who vetoed the legislation.
"First the Chinese authorities gave us a massacre, and then they gave us a masquerade," Pelosi said at a news conference outside the U.S. Capitol in 1990.
Pelosi wrangled Democratic and Republican votes to override Bush's veto -- embarrassing Bush, who once served as a top U.S. representative to China.
While the veto override effort fell several votes short in the Senate, the Washington post reported, the administration eventually issued an executive order that accomplished Pelosi's goals of protecting the Chinese students in the United States.
Later, on an official visit to China in 1991, Pelosi and two congressmen were briefly detained by Chinese police, after unfurling a small banner in protest to commemorate pro-democracy protesters killed near Tiananmen Square.
"We've been told now for two days in private meetings with Chinese officials that there is no prohibition on freedom of speech in China," Pelosi said, according to the Baltimore Sun. "This does not conform to what we were told."
The international incident cemented Pelosi's position as a chief China critic. She "has been a strong advocate of human rights for a very long time," Glaser told ABC News.
Pelosi ruffled feathers on a subsequent trip to China: In 2009, she hand-delivered a letter to Hu Jintao, China's president at the time, calling for the release of political prisoners.
Challenging China's trade status and taking on her own party
In the 1990s, Pelosi repeatedly clashed with leaders of her own party over the United States' improving economic relationship with China and its ascension to the World Trade Organization.
She criticized and challenged President Bill Clinton's efforts to improve trade relations between the two countries, arguing against normalizing trade relations and decoupling the economic relationship from concerns about Beijing's human rights record and the transfer of technology to countries hostile to the United States.
"I am disappointed that President Clinton has chosen to continue a failed policy," she said in a statement when normal relations were extended in 1997. "Since he delinked trade from human rights three years ago, the human rights situation in China and Tibet has deteriorated, the U.S. trade deficit with China has soared, and China's authoritarian government has continued its sale of nuclear, chemical, missile and biological weapons technology to dangerous countries, including Iran.'
Years later, her positions even led to one of her rare breaks with President Obama and his administration.
According to Newsweek, Pelosi in 2009 helped scuttle the confirmation chances of Obama's initial pick to lead the National Intelligence Council, over comments he had made about the Tiananmen Square massacre.
(She did not deny her position when later asked about the episode by the Huffington Post.)
"It's a cheap shot for both Americans or Chinese to accuse her of sort of doing this as some sort of provocation when her commitment to the region and activists has been consistent and unwavering," said Samuel Chu, the founder and President of the Campaign for Hong Kong, whose father, a prominent/veteran pro-democracy activist, met with Pelosi in Hong Kong on one of her early visits to the region.
Olympic boycotts over Tibet and Chinese forced labor
Pelosi called for the U.S. to impose diplomatic boycotts of the summer and winter Olympics hosted by China in Beijing in 2008 and 2022, respectively.
In 2008, she called for President Bush and other world leaders to boycott the opening ceremonies of the Summer Olympics to show support for Tibetans pushing for independence from China, and condemned the International Olympic Committee for awarding the games to China given its human rights record.
"If freedom-loving people don't speak out against China's oppression of people in Tibet, we have lost all moral authority to speak out against any oppressed people," Pelosi said on a visit to India and the Dalai Lama's government-in-exile.
"I don't think China should have gotten the Olympic Games to begin with," Pelosi told ABC's "Good Morning America" in 2008. "I had a resolution in the Congress which was very popular, and bipartisan support on it. But they did get them with the promise that they would open up more and have better respect for human rights and freedom of expression. They have not honored that."
Years later, when China prepared to host the Winter Olympics, Pelosi repeated her calls for a diplomatic boycott - this time over China's treatment of its Uyghur Muslim minority.
"We cannot proceed as if nothing is wrong about the Olympics going to China," she said at a congressional hearing.
China's Foreign Ministry blasted Pelosi's statements and said she was "full of lies and disinformation" in calling for a diplomatic boycott of the Winter Games.
Around the same time, she worked across party lines with Republicans to pass legislation to sanction China for selling goods to America made with Uyghur Muslim forced labor -- which President Biden later signed into law.
"None of that would have been possible without her leadership," Rep. Jim McGovern, D-Mass., told ABC News. "She's unrelenting."