Officials fear China could attack Nancy Pelosi's plane if she visits Taiwan as Beijing doubles down on threat saying U.S will 'bear all consequences': Biden will speak with President Xi Jinping tomorrow to bring countries back from the brink 

U.S. officials today said they fear that China could attack Nancy Pelosi's plane if she flies to Taiwan as Beijing doubled down on their threat to take 'firm and strong measures' if the House speaker visits the island. 

Those fears have meant that if Pelosi does travel to Taiwan, which is still an uncertainty, the U.S. military would increase its movement of forces and assets in the Indo-Pacific region, officials said. 

The officials declined to provide details of their plans, but said that fighter jets, ships, surveillance assets and other military systems would likely be used to provide overlapping rings of protection for her flight to Taiwan and any time on the ground there. 

Any foreign travel by a senior U.S. leader requires additional security. But officials said this week that a visit to Taiwan by Pelosi - who would be the highest-ranking U.S. elected official to visit the island since 1997 - would go beyond the usual safety precautions for trips to less risky destinations. 

It comes as China warned today that Washington would 'bear the consequences' if Pelosi visits Taiwan - days after threatening to take 'resolute and forceful measures' against the US if the trip goes ahead.

'If the US pushes ahead and challenges China's bottom line... the US side will bear all the consequences arising therefrom,' Chinese foreign ministry spokesman Zhao Lijian said at a regular press conference.  

Self-governed Taiwan's 23 million people live under the constant threat of invasion by authoritarian China, which views the island as its territory and has vowed to one day seize it, by force if necessary. 

Amid the soaring tensions between the US and China, President Joe Biden and President Xi Jinping are expected to talk on Thursday in what will be the fifth call between the leaders. 

'The Chinese military will not turn a blind eye to it, and will respond by taking strong measures to thwart any external interference and 'Taiwan independence' secessionist attempts, to resolutely defend national sovereignty and territorial integrity,' Tan said. 

Under its one-China policy, Washington does not have official diplomatic relations with Taiwan, but is bound by U.S. law to provide the island with the means to defend itself. The White House has been quick to reiterate that stance has not changed despite speculation over a possible trip by Pelosi. 

U.S. officials say that the prospects of an intercept or show of force by Chinese aircraft near Pelosi's flight raises concerns, prompting the need for American aircraft and other assets to be nearby. 

Taiwan today, with its own constitution and democratically-elected leaders, is widely accepted in the West as an independent state. But its political status remains unclear.