US House of Representatives Speaker Nancy Pelosi kicked off a closely-watched Asia tour on Monday in Singapore as China warned that its military would never "sit idly by" if she were to visit Taiwan, the self-ruled island claimed by Beijing.
Amid widespread speculation over whether she would make a stop in Taiwan, Pelosi's office announced on Sunday that she was leading a Congressional delegation to the region that would include visits to Singapore, Malaysia, South Korea and Japan. It did not mention Taiwan.
Chinese foreign ministry spokesman Zhao Lijian said that it would be "a gross interference in China's internal affairs" if Pelosi visits Taiwan, and warned that it would lead to "very serious developments and consequences."
"We would like to tell the United States once again that China is standing by, the Chinese People's Liberation Army will never sit idly by, and China will take resolute responses and strong countermeasures to defend its sovereignty and territorial integrity," Zhao told a regular daily briefing.
Asked what kind of measures the PLA might take, Zhao said: "if she dares to go, then let us wait and see.”
China views visits by US officials to Taiwan as sending an encouraging signal to the pro-independence camp in the island. Washington does not have official diplomatic ties with Taiwan but is bound by US law to provide the island with the means to defend itself.
A visit by Pelosi, who is third in the line of succession to the presidency and a long-time critic of China, would come amid worsening ties between Washington and Beijing. Republican Newt Gingrich was the last House speaker to visit Taiwan, in 1997.
During a phone call last Thursday, Chinese President Xi Jinping warned his US counterpart Joe Biden that Washington should abide by the one-China principle and "those who play with fire will perish by it".
Biden told Xi that US policy on Taiwan had not changed and that Washington strongly opposes unilateral efforts to change the status quo or undermine peace and stability across the Taiwan Strait.
On Monday, Taiwan Premier Su Tseng-chang did not directly respond when asked whether Pelosi will visit on Thursday, as local media have speculated.
"We always warmly welcome visits to our country by distinguished foreign guests," he told reporters in Taipei.
Shi Yinhong, an international relations professor at Renmin University in Beijing, said that if Pelosi visits Taiwan it would prompt the strongest counter-measures by Beijing in years, but he did not expect that to trigger major military conflict.
"China has reiterated in no ambiguous terms its opposition to Taiwan separatism. The U.S. has reiterated many times its one-China policy has not changed and that it is against any change to the status quo by either side of the Taiwan Strait," he said.
"Unless by accident, I am sure neither side would intentionally take military action that could lead to a major security risk.”
On Monday, Pelosi and her delegation met with Singapore Prime Minister Lee Hsien Loong, discussing issues including cross-strait relations, the Ukraine war and climate change, Singapore's foreign ministry said.
"PM Lee highlighted the importance of stable US-China relations for regional peace and security," it said.
Beijing considers Taiwan to be part of its territory and has never renounced using force to bring the island under its control. Taiwan rejects China's sovereignty claims and says only its people can decide the island's future.
Last Wednesday, Biden told reporters he thought the US military believed a Pelosi visit to Taiwan was "not a good idea right now".