China and South Korea have criticised new tariffs on imported washing machines and solar panels as part of Donald Trump's "America First" trade policy.
The tariffs, announced late on Monday, aim to protect US manufacturers from foreign competition, but opponents fear they could mark the opening salvo in a trade war if the Asian nations respond in kind.
The move may constitute a"violation of WTO provisions,"said South Korean trade minister Kin Hyuan-chong.
Adding to criticism from environmentalists, who say increasing the cost of solar panels will stunt renewable energy uptake in the US, China's government spokesman Way Hejun expressed "strong dissatisfaction" with the move.
"Together with other WTO members, China will resolutely defend its legitimate interests," he said.
The new duties will mainly effect washing machine producers in South Korea and solar panel manufacturers in China.
The tax on solar panels is not as high as US manufactures had hoped, set at 30 per cent for the first year and falling to 15 per cent by the fourth.
However, 2.5 gigawatts of cells will be allowed into America tariff-free each year.
Meanwhile, the first 1.2 million imported residential washing machines will see a 20 per cent duty in the first year, with all imports above that number slapped with a tax of 50 per cent.
The figures will drop to 16 per cent and 40 per cent respectively by the third year.
South Korea, whose washing machine manufacturers include Samsung and LG, called the duties "excessive" and threatened to complain to the World Trade Organization (WTO).
The US is by far the most protectionist when it comes to global trade
American manufacturers, who have for long campaigned for protection against cheap foreign imports, welcomed the news.
Jeff Fettig, chairman of US washing machine makers Whirlpool, said, "This announcement caps nearly a decade of litigation and will result in new manufacturing jobs in Ohio, Kentucky, South Carolina and Tennessee."
The tougher trade policy was first approved by President Trump after an International Trade Commission report announced in September last year that domestic washing machine manufacturers are being hurt by cheap imports from Asia.
The new tariffs constitute the president's most decisive move on trade since pulling out of the Trans-Pacific Partnership (TPP) when first elected.
The move could come as Mr Trump prepared to travel to Switzerland to attend the World Economic Forum in Davos this week.
The theme of this year's meeting is "creating a shared future in a fractured world", but it is expected that the president will use his attendance to push his America First agenda.
There has already been one protest against Mr Trump's participation in the forum, with hundreds anti-globalization demonstrators marching through Switzerland's capital city of Bern earlier this month.
Another demonstration, dubbed Trump: Welcome to Hell, has been called for the opening of the meeting on Tuesday.