President Donald Trump said Tuesday he has ordered his administration to raise tariffs on Canadian steel and aluminum imports by an additional 25%, bringing the total duties to 50%.

The new policy will go into effect Wednesday morning, Trump said in a Truth Social post that also repeated his calls for Canada to be absorbed into the U.S. as the “Fifty First State.”

Trump said he was imposing the latest tariffs in response to a decision by Ontario’s government to slap a 25% tax on electricity exports to the U.S.

That move by Ontario Premier Doug Ford was itself issued in retaliation to the sweeping 25% tariffs that Trump had placed on imports from Canada.

“Based on Ontario, Canada, placing a 25% Tariff on “Electricity” coming into the United States, I have instructed my Secretary of Commerce to add an ADDITIONAL 25% Tariff, to 50%, on all STEEL and ALUMINUM COMING INTO THE UNITED STATES FROM CANADA, ONE OF THE HIGHEST TARIFFING NATIONS ANYWHERE IN THE WORLD,” Trump wrote on Truth Social on Tuesday morning.

“This will go into effect TOMORROW MORNING, March 12th,” he wrote.

The Dow Jones Industrial Average extended its losses after Trump’s announcement, falling more than 400 points, while the S&P 500 dropped 0.6% and the Nasdaq Composite fell 0.1%.

Markets are already reeling from the impact of Trump’s tariffs and broader fears of a recession.

Minutes after Trump’s announcement, Ford said he would keep his countermeasure on U.S. energy in place.

“We will not back down. We will be relentless,” Ford said on MSNBC. “I apologize to the American people that President Trump decided to have an unprovoked attack on our country, on families, on jobs, and it’s unacceptable.”

Trump in Tuesday’s post also demanded that Canada “immediately drop” an “Anti-American Farmer Tariff” on certain U.S. dairy products, warning that he “will shortly be declaring a National Emergency on Electricity within the threatened area.”

“This will allow the U.S to quickly do what has to be done to alleviate this abusive threat from Canada,” he wrote.

The president also declared that if Canada does not lift other “egregious, long time Tariffs” on the U.S., he will “substantially increase” tariffs on auto imports on April 2.

Doing so will “essentially, permanently shut down the automobile manufacturing business in Canada,” Trump wrote.

Trump, who frequently praises tariffs as an economic multitool, has hyped April 2 as the date when he will impose widespread “reciprocal tariffs” on other countries that have their own duties on U.S. goods.

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