They said China could respond by flying fighter jets further into Taiwan’s self-declared air defence zone, triggering a response from Taiwan. Chinese warplanes have flown into Taiwan’s self-declared air defence zone identification zone on numerous occasions in recent months.
Although this doesn’t break International law it usually prompts a defensive response from Taiwan including the scrambling of fighter jets.
Chinese planes have not entered the island’s territorial airspace which extends 12 nautical miles from its coastline.
The US State Department has called on Beijing to stop its intimidation of Taiwan.
Ms Pelosi, who is the US Speaker of the House of Representatives, has been planning the trip in the coming weeks, sources have told CNN.
Should the visit go ahead the veteran lawmaker would be the highest ranking US official to visit Taiwan since then-Speaker Newt Gingrich in 1997.
Tensions between Beijing and Washington have soured in recent months over the issue of Taiwan.
The Chinese Communist Party has long claimed Taiwan as part of its territory and has repeatedly vowed to “reunify” with the island of 24 million people by force if necessary .
Following the Communist victory in the Chinese civil war in 1949 supporters of the KMT nationalists led by Chiang Kai shek fled to the island.
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US President Joe Biden expressed doubt about a possible visit on Wednesday citing concerns from the military.
He said: “I think that the military thinks it’s not a good idea right now, but I don’t know what the status is.”
Col. Dave Butler, Joint Chiefs of Staff spokesman, said the US military “in general” briefs decision makers on military assessments.
He said: “We talk about what adversaries may do, discuss logistics and military plans and readiness.”
On Thursday Ms Pelosi emphasised the importance of supporting Taiwan but said she was unclear about the military concerns mentioned by Mr Biden.
She said: “I think what the President was saying is that maybe the military was afraid of my plane getting shot down or something like that. I don’t know exactly.”