If Donald Trump goes ahead with threatened 25 per cent tariffs on steel and aluminum, that would stack on top of the 25 per cent across-the-board tariff on Canadian goods that he has already vowed, the White House confirmed to Global News.

That means the tariffs on Canadian steel and aluminum imports into the U.S. would total 50 per cent.

On Feb. 1, the U.S. president signed an executive order imposing tariffs on Canadian and Mexican goods.

“I have implemented a 25% Tariff on Imports from Mexico and Canada (10% on Canadian Energy), and a 10% additional Tariff on China,” Trump said in a statement at the time.

Prime Minister Justin Trudeau announced Canada would impose retaliatory tariffs worth $155 billion in an address to the nation later that night.

A day before the tariffs were to go into effect, Trudeau and Trump had a phone call after which Trump decided to pause the tariffs for 30 days.

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But the thaw was short-lived.

Trump on Monday signed a pair of presidential proclamations that will impose 25 per cent tariffs on foreign steel and aluminum on March 12, with no exceptions or exemptions.

“It’s a big deal. This is the beginning of making America rich again,” Trump said as he signed the orders in the Oval Office.

The Trump administration said the move was meant to shore up the U.S. steel and aluminum industries and to protect America’s economic and national security.

While Canada has promised a series of measures to curb the flow of fentanyl at the border – which Trump says is the reason he is imposing broad tariffs – the deadline will be up in the first week of March.

Trump has also threatened tariffs on Canadian vehicles of between 50 and 100 per cent.

During previous 25 per cent tariffs on steel and 10 per cent on aluminum in Trump’s first term, steel exports to the U.S. dropped 38 per cent during the year the tariffs were in place, according to Statistics Canada, while aluminum exports fell by more than half.

–with files from Global’s Reggie Cecchini and David Aikin