Singapore Prime Minister Lee Hsien Loong on Tuesday warned the United States against aggressively challenging China, saying Washington's increasingly hard-line views could be "very dangerous."

He said the United States had moved from an approach of healthy competition with China to the view that America "must win, one way or another."

"There is (US) bipartisan consensus today on one thing, which is relations with China," he told the Aspen Security Forum.

"But their stance is to take a hard line. And I'm not sure that is the right consensus," the Singaporean leader said.

"I don't know whether Americans realise what a formidable adversary they would be taking on if they decide that China is an enemy.

"In this situation, I would say to both, pause, think carefully before you fast-forward, it's very dangerous," he said.

"It's vital for the US and China to strive to engage each other to head off a clash, which would be disastrous for both sides, and the world."

Lee, who is seen as someone with insights into the leadership of both countries, said Washington's tough views of China are increasingly matched by Chinese belief that the United States can't be trusted and wants to block its emergence.

He criticized the Biden administration's show of toughness in its first high-level bilateral meeting with the Chinese in Anchorage, Alaska in March.

"The reality is neither side can put the other one down," he said.

But Lee cheered the Biden administration's return to a "more conventional" foreign policy after the disruptive approach of his predecessor Donald Trump.

"Countries are looking for long term strategic consistency from the US," he said, and policy that is "reliable and predictable."

He said Taiwan is a particular potential flashpoint.

"I don't think they want to make a unilateral move" like invading Taiwan, he said of Beijing.

"But I think there is a danger, and the danger is of mass miscalculation."

He expressed appreciation for US Defense Secretary Lloyd Austin's comments in Singapore last week, warning against any change in the status quo of the Taiwan situation.

"I think if that careful position is clearly and consistently maintained, then we are able to maintain peace and stability across the Taiwan Strait," Lee said.

At any rate, he added, "you're in for a quite difficult period."