The Pentagon chief made the remarks at an annual security forum in Singapore, where he pressed US allies and partners in Asia to step up defence spending.

"The threat China poses is real and it could be imminent," Hegseth said at the Shangri-La Dialogue, adding that Beijing "hopes to dominate and control" Asia.

Beijing's military was building the capabilities to invade Taiwan, training every day and "rehearsing for the real deal", he said.

Citing stepped-up cooperation with allies including Japan and the Philippines, and a deepening military partnership with India, Hegseth said the United States was "reorienting toward deterring aggression by communist China".

He called on Washington's allies and partners in the region to ramp up spending on their militaries in the face of the Chinese threat.

"It's hard to believe a little bit... that I'm saying this, but thanks to President Trump, Asian allies should look to countries in Europe for a newfound example," Hegseth said, citing pledges by NATO members including Germany to move toward US President Donald Trump's spending target of five percent of GDP.

"Deterrence doesn't come on the cheap."