In a decisive move on Thursday, President Trump announced a halt to trade negotiations with Canada, attributing the decision to an advertising campaign that highlighted former President Ronald Reagan’s cautionary remarks on the potential dangers of tariffs. This ad campaign emerged amid ongoing trade tensions between the United States and Canada.

Trump took to Truth Social to express his concerns, accusing Canada of using the advertisement as a tool to meddle in a critical Supreme Court case that could determine the extent of Trump’s power to implement broad tariffs against foreign nations.

“Tariffs play a crucial role in safeguarding the national security and economic interests of the United States. Due to Canada’s unacceptable actions, I am terminating all trade negotiations with them,” Trump declared.

The campaign, launched earlier this month by Ontario Premier Doug Ford—who has often been at odds with Trump—features a 1987 speech by Reagan. In this historical clip, Reagan reflects on tariffs that were imposed on Japanese imports and warns of the potential long-term impacts of trade conflicts on consumers.

“High tariffs inevitably lead to retaliation by foreign countries and the triggering of fierce trade wars. Then the worst happens,” Reagan warns in the ad. “Markets shrink and collapse, businesses and industries shut down, and millions of people lose their jobs.”

Trump in August announced a 35 percent tariff on all Canadian goods, though products covered under the 2020 U.S.-Mexico-Canada trade agreement were exempt.

Canada is one of the United States’ top trading partners, and their economies are heavily intertwined when it comes to certain products. But Trump has repeatedly argued the U.S. does not need Canadian goods, and that Canada is far more reliant on America for its economy.

Canadian Prime Minister Mark Carney visited the White House earlier this month, where he and Trump discussed trade. 

“There’s still great love between the two countries, but you know American people want product here, they want to make it here,” Trump said during the meeting. “We are competing for the same business. That’s the problem.”