Washington: US Treasury Secretary Steve Mnuchin says President Donald Trump has no intention of backing down and isn't worried about a trade war despite threats of retaliation from China over US plans to impose tariffs on up to $US60 billion in Chinese goods.

"We are going to proceed with our tariffs. We're working on that," Mnuchin told Fox News Sunday. "So, as President Trump said, we're not afraid of a trade war, but that's not our objective."

Fears of a trade war between the US and China have sent US stock prices tumbling. The Dow Jones Industrial Average and the S&P 500 both lost nearly 6 per cent by the end of last week.

A presidential memorandum signed by Trump last week will target up to $US60 billion in Chinese goods with tariffs over what his administration says is misappropriation of US intellectual property, but only after a 30-day consultation period that starts once a list is published.