The United States insisted yesterday it was not turning its back on the world as President Donald Trump prepared to sell his "America First" message to sceptical fellow leaders in Davos.

European leaders including French President Emmanuel Macron and German Chancellor Angela Merkel were set take the stage at the World Economic Forum later yesterday in advance of Trump's surprise visit, to defend the liberal international order after a year-long assault by the US president.

The protectionist Trump, fresh from angering China and South Korea with new tariffs on solar panels and large washing machines, will close the annual conference with a speech on Friday. Top US officials said his trip was intended to defend US interests while also promoting international partnerships.

"This is about an America First agenda but America First does mean working with the rest of the world," Treasury Secretary Steven Mnuchin told reporters at the gathering of heads of government, business tycoons, campaigners and celebrities.

"It just means that President Trump is looking out for American interests, no different than other leaders look out for their own," he added.

US Commerce Secretary Wilbur Ross, also in Davos, staunchly defended Monday's tariffs announcement.

"Trade wars are fought every single day... and unfortunately every single day there are various parties violating the rules and trying to take unfair advantage," Ross said.

"Trade wars have been in place for quite a little while. The difference is the US troops are now coming to the ramparts," he added.

Mnuchin, however, said the United States was not bent on a "race to the bottom" on tax rates by luring away foreign investors unfairly.