China slammed the United States for its "dangerous" decision to congratulate Taiwan's President Tsai Ing-wen on her inauguration on Wednesday, as the self-ruled island became the latest flashpoint between the world's two largest economies.
Taiwanese voters handed Tsai a second term with a landslide win in January, a vocal rebuke of China's ongoing campaign to isolate the island.
She was sworn in for another four years at a ceremony on Wednesday in which she called on China to live peacefully alongside a self-ruled Taiwan and for a lowering of tensions.
But a congratulatory note from US Secretary of State Mike Pompeo hailing Tsai's "courage and wisdom" sparked a rebuke from Beijing, which bristles at any formal recognition of Taipei.
"It is extremely wrong, and it's also very dangerous," China's defence ministry said.
Beijing's foreign ministry said it was "extremely indignant" at the message and accused Washington of breaching its diplomatic commitments.
Tsai, 63, is loathed by Beijing because her party views Taiwan as a de facto sovereign state and not part of "one China".
Since she first came to office in 2016, China has rebuffed offers of talks and ramped up economic, military and diplomatic pressure on the island.
'A way to coexist'
Beijing views Taiwan as part of its territory and has vowed to seize it by force if necessary.
Washington diplomatically recognises Beijing but remains a major ally for Taiwan and is bound by Congress to provide arms sales to ensure its defence.
Under President Donald Trump, ties between Taipei and Washington have further warmed as China-US relations plummet.
Beijing envisages a "one country, two systems" model that – like nearby Hong Kong – would allow Taiwan to keep some freedoms while submitting to Chinese mainland rule.
But Tsai made clear during her inauguration speech that the concept was a non-starter.
"We will not accept the Beijing authorities' use of 'One country, two systems' to downgrade Taiwan and undermine the cross-strait status quo," she said.
Tsai renewed her offer of talks with Beijing.
"Both sides have a duty to find a way to coexist over the long term and prevent the intensification of antagonism and differences," she added.
Taiwan has been ruled separately from the mainland since 1949 after the Nationalists lost a civil war to the Communists and fled to the island to set up a rival government.
For decades, Taiwan's leaders – and many voters – saw themselves as the true representatives for all of China, even as the vast majority of nations switched diplomatic recognition to Beijing.
But as the island moved from an autocracy to a democracy from the 1990s, a distinct Taiwanese identity has emerged with many no longer seeking any kind of reunification with China.
That has caused growing concern in Beijing, which says any formal declaration of independence by Taipei would cross a red line.
After Tsai's speech, China's Taiwan Affairs Office warned it would "never tolerate" the island's separation.
Analysts said Tsai's speech was in fact conciliatory.
"President Tsai has drawn clear lines and established a few non-negotiables, while making sufficient rhetorical concessions that, should it want to, the leadership in Beijing could meet her half-way," J. Michael Cole, a Taipei-based fellow with the University of Nottingham's Taiwan Studies Programme, said.
"She is also assuring the US that she won't be rash and won't become a troublemaker," added Fan Shih-ping, a political scientist at National Taiwan Normal University.
Tsai's inauguration was also a chance for her to celebrate Taiwan's successful fight against the coronavirus.
Despite its close proximity and economic links with China, Taiwan has managed to contain its own outbreak to just seven deaths and has sent protection equipment aid packages around the world.