Trump to hit China, Europe with steep steel, aluminum 'tariffs'
President Donald Trump addressed the nation following the Florida school shooting. (AFP / Mandel NGAN)

Despite fierce opposition from inside the White House, US President Donald Trump announced punishing steel and aluminum tariffs Thursday, teeing up a possible trade war with China and Europe.

Trump ended rumor and counter-rumor about his administration’s intent by saying that "next week" he would sign off on measures designed to protect US producers.

Meeting in the Cabinet Room with representatives of US business, Trump announced tariffs of 25 percent on steel products and 10 percent on aluminum, materials that are the lifeblood of the construction and manufacturing sectors.

"We're going to be instituting tariffs next week," Trump said, adding they will be in place "for a long period of time."

The announcement is sure to be greeted with fury in Beijing and Brussels, where officials have already warned of countermeasures.

But Trump's decision, which leans on a rarely used national security provision in global trade accords -- could also have a deep impact on producers in South Korea and Canada.

The timing of the announcement will be seen as especially provocative in China, coming as top envy Liu He visits Washington.

Liu recently ascended to the country's powerful politburo and is tipped as a possible future chair of the Chinese central bank. He had been due to meet US officials, although not the president.

Sources familiar with Trump's decision say he came up against stern opposition from aides like Gary Cohn, who argued the move could ultimately damage US industry.

There was doubt about whether he would pull the trigger up to the last moment.

But it was trade hawks like Peter Navarro -- who, after weeks on the sidelines was in the cabinet room as Trump made his remarks -- who appeared to have won the day.

The same sources say that it is not impossible that the shock announcement is followed by carve outs that make the measures more palatable to allies in Europe, Canada and South Korea.