Washington: The Central Intelligence Agency (CIA) chief has warned that China appears to be determined on using force in Taiwan but Russia's experience in Ukraine has affected Beijing's calculations on when and how - rather than whether to invade.

CIA Director William Burns said that China likely saw in Ukraine that "you don't achieve quick, decisive victories with underwhelming force", Al Jazeera reported.

China repeatedly claims that Taiwan is part of its territory and has not ruled out using force to take control of the island.

Speaking at the Aspen Security Forum, Burns said that China was "unsettled" when looking at Russia's five-month-old war in Ukraine, which he characterised as a "strategic failure" for President Vladimir Putin because he had hoped to topple the Kyiv government within a week.

"Our sense is that it probably affects less the question of whether the Chinese leadership might choose some years down the road to use force to control Taiwan, but how and when they would do it," Burns said as quoted by Al Jazeera.

The CIA Director's comments came amid the continued tension between Washington and Beijing over a slew of issues including trade and Taiwan, as United States President Joe Biden revealed plans for a call with President Xi Jinping - the first between the two leaders in four months.

"I think I'll be talking to President Xi within the next 10 days," US President Joe Biden told reporters after he returned from the state of Massachusetts.

The US calls China its main strategic rival and says high-level engagement is important to keeping the difficult relationship stable and prevent it from veering inadvertently into conflict.

Earlier, Biden said the US military believes it is not a "good idea" for House of Representatives Speaker Nancy Pelosi to travel to Taiwan as planned.

Meanwhile, China warned against Pelosi's upcoming visit to Taiwan next month saying that it will act strongly and take countermeasures if the US side insists on going ahead with the visit.

Burns played down speculation that Xi could make a move on Taiwan after a key Communist Party meeting later this year but said the risks "become higher, it seems to us, the further into this decade that you get", according to Al Jazeera.

"I wouldn't underestimate President Xi's determination to assert China's control" over Taiwan, he said.

Speaking before Burns at the forum in Colorado's Rocky Mountains, China's ambassador to the United States, Qin Gang, said that Beijing still preferred "peaceful reunification", but he accused the US of supporting "independence" forces in Taiwan.