President Donald Trump said on Thursday he was terminating trade talks with Canada, threatening once again to upend the crucial economic relationship between the United States and its second-biggest trading partner.

Trump said he canceled the talks in response to an advertisement released last week by the government of Canada’s Ontario province, which featured audio from a speech by former US President Ronald Reagan criticizing tariffs on foreign goods.

In the 1987 speech, Reagan lambasted tariffs as hurting “every American worker and consumer” and “triggering fierce trade wars.”

After the ad aired, the Ronald Reagan Foundation claimed it “misrepresents” the speech, and that the Ontario government had not asked permission to use the clip.

By Thursday night, Trump had taken to social media to blast the ad.

“The Ronald Reagan Foundation has just announced that Canada has fraudulently used an advertisement, which is FAKE, featuring Ronald Reagan speaking negatively about Tariffs,” he wrote on Truth Social.

He claimed the ad aimed to “interfere with the decision of the U.S. Supreme Court, and other courts,” and defended tariffs as critical to the US economy and national security.

“Based on their egregious behavior, ALL TRADE NEGOTIATIONS WITH CANADA ARE HEREBY TERMINATED,” he wrote.

CNN has reached out to Canadian Prime Minister Mark Carney’s office for comment, as well as the office of Dominic LeBlanc, the minister overseeing US-Canada trade.

Ontario Premier Doug Ford had first posted the ad online on October 16, writing in a caption: “Using every tool we have, we’ll never stop making the case against American tariffs on Canada. The way to prosperity is by working together.”

A disclaimer under the ad states that it was not approved or sponsored by the Ronald Reagan Presidential Library or the Ronald Reagan Presidential Foundation.

Along with its statement, the Ronald Reagan Foundation offered a link to the full unabridged version of Reagan’s decades-old speech – in which he speaks at greater length about why he opposes tariffs. “More than five million American jobs are directly tied to the foreign export business, and additional millions are tied to imports,” he said in one quote, which was not included in the ad.

The description for the full YouTube video lists the speech as “unrestricted” in both access and use.

Since Trump took office, the centuries-long friendship between the US and Canada has broken down amid bruised feelings over tariffs and Trump’s threat to make Canada the 51st US state. Many Canadians are boycotting American goods, and refusing to travel to the US.

Canada has long been one of the US’ top trading partners; last year, the US imported $411.9 billion worth of goods from Canada, according to government figures.

But Canada’s economy has been hit hard by Trump’s steep sectoral tariffs on autos, steel, aluminum, lumber, and energy – some of the country’s key exports to the US. Those fall under the US-Mexico-Canada Agreement (USMCA), which Trump brokered during his first term and will be under mandatory review next year. Canada’s unemployment rate is now at its highest point in nine years.

“This is the last thing that either country needs,” Jack Buffington, director of the supply chain program at the University of Denver, told CNN after Trump’s announcement. “We need to stabilize the North American supply chain, particularly given the challenges that the US has with China.”

Carney won an election in April with a strident message for Canadians, warning that their relationship with America would change dramatically in the coming years. He has fostered relationships with other Western countries instead; on Thursday, before Trump’s post, he had announced on X that Canada plans to double its non-US exports in the next decade.

“Our core mission is to build a stronger economy — one that doesn’t rely on a single trade partner,” he wrote on X.

The economic relationship has reached a boiling point several times over the course of Trump’s second term. Earlier this year, in the relationship’s tensest moment, Ford threatened to halt exports of Canadian electricity to the United States, which would have sent US energy bills surging. But he ultimately backed off that threat. Trump has also threatened to call off talks with Canada in the past, only to restore negotiations.

Tensions have eased slightly in recent months, however, with Carney meeting Trump at the Oval Office earlier this month. There, Trump joked about a “merger” of the two countries but also praised his counterpart as a “world-class leader.”

LeBlanc, the Canadian trade minister, said negotiators for both countries had left with directions to “quickly land deals” on steel, aluminum and energy. He described the meeting between leaders as “successful, positive, substantial.”

That brief warming of ties, it seems, is over – at least for now.

This story has been updated with additional information.

CNN’s Rhea Mogul and David Goldman contributed reporting.