(WASHINGTON) -- President Donald Trump on Tuesday escalated a trade war with Canada, imposing a fresh round of tariffs on steel and aluminum products, threatening additional duties, and reiterating a call for Canada to give up its sovereignty and become a part of the United States.
Top Canadian officials responded forcefully, saying the country would keep its countermeasures in place until Trump withdraws U.S. tariffs.
Trump announced the new policies a day after Ontario slapped a 25% surcharge on electricity sent to the U.S., saying that he is adding another 25% tariff on Canadian steel and aluminum, bringing the total to 50%.
Trump said in a post on Truth Social that the increased tariff "will go into effect TOMORROW MORNING, March 12th."
The U.S. imports more steel and aluminum from Canada than any other country.
In an interview on Tuesday after Trump's announcement, Ontario Premier Doug Ford urged Trump to withdraw the tariffs, threatening to further escalate the standoff by shutting off electricity Canada supplies to the U.S.
"That's the last thing I want to do," Ford told CNBC. "I want to send more electricity down to the U.S., to our closest allies."
"Is it a tool in our toolkit? 100%. And as [Trump] continues to hurt Canadian families, Ontario families, I won't hesitate to do that," Ford continued.
A spokesperson for Canada's incoming Prime Minister Mark Carney described Trump's latest tariffs as an "attack on Canadian workers, families and businesses."
"My government will keep our tariffs on until the Americans show us respect and make credible, reliable commitments to free and fair trade," the spokesperson added in a statement to ABC News.
Trump also said in his post that he will "shortly be declaring a National Emergency on Electricity" in the area impacted by the tariffs from Canada. He said that the national emergency will "allow the U.S to quickly do what has to be done" to respond to the tariff from Canada, without providing any specifics on what actions the U.S. might take.
Earlier Tuesday, Ford urged Trump to reconsider his tariffs, saying that they are "causing chaos."
"Markets are tanking. He needs to drop his tariffs and come to the table to negotiate a fair trade deal. Until he does, we won’t back down," Ford said in a post on X.
The announcement from Trump escalated a trade war between set off last week after the U.S. imposed 25% tariffs on imports from Canada. In a near-immediate response, Canada slapped a 25% retaliatory tariff on $30 billion worth of goods. Tariffs on an additional $125 billion worth of products will take effect in 21 days, then-Prime Minister Justin Trudeau said
Trudeau sharply criticized the tariffs, calling them a "dumb" policy that does not "make sense."
The tit-for-tat measures reignited a trade war that had been averted a month earlier, when Trump paused the implementation of tariffs after reaching an agreement with Canada on border enforcement.
In late February, Trump alleged that illicit drugs such as fentanyl had continued to enter the U.S. through Canada, despite the agreements reached weeks earlier to address the issue.
Since September, nearly all fentanyl seized by the U.S. came through the Southern border with Mexico, according to the U.S. Customs and Border Patrol (CBP) agency. Less than 1% of fentanyl was seized at the northern border with Canada, the CBP found.
The reason for the tariffs is based on a false allegation about Canada as a major source of drugs entering the U.S., Trudeau said last week.
As part of his announcement on Tuesday, Trump threatened to impose additional retaliatory tariffs on Canada if duties on U.S. goods remain in place.
"If other egregious, long time Tariffs are not likewise dropped by Canada, I will substantially increase, on April 2nd, the Tariffs on Cars coming into the U.S. which will, essentially, permanently shut down the automobile manufacturing business in Canada," Trump said in the Truth Social post.
He also called on Canada to drop their tariffs on dairy farmers, and again asserted that Canada should become America's 51st state.
"The artificial line of separation drawn many years ago will finally disappear, and we will have the safest and most beautiful Nation anywhere in the World – And your brilliant anthem, “O Canada,” will continue to play, but now representing a GREAT and POWERFUL STATE within the greatest Nation that the World has ever seen!," Trump said in the post.
This is a developing story. Check back for updates.
ABC News' William Gretsky contributed to this report.
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