US President Donald Trump has said he is immediately ending all trade negotiations with Canada.
In a post on Truth Social, Trump wrote that the country had run an advert featuring former US President Ronald Reagan speaking negatively about tariffs.
Based on their egregious behavior, ALL TRADE NEGOTIATIONS WITH CANADA ARE HEREBY TERMINATED, Trump wrote late on Thursday.
The US president has imposed a 35% levy on Canadian imports, although he has allowed exemptions for goods that fall under the USMCA - a free trade agreement with Mexico and Canada that Trump negotiated during his first term.
Trump said the video, sponsored by the Ontario government, was designed to interfere with the US Supreme Court, referring to an upcoming decision in November on whether Washington's sweeping global tariffs are legal.
The court's decision represents the biggest test of Trump's presidential authority and signature economic policy, potentially forcing the US to refund billions collected in tariffs.
In the minute-long advert published last week, Reagan's voice is heard narrating over images that include the New York Stock Exchange and cranes adorned with both US and Canadian flags.
The video excerpts a 1987 national radio address by Reagan that focused on foreign trade.
In the post accompanying the video advert, Ontario Premier Doug Ford wrote that we'll never stop making the case against American tariffs on Canada.
Ford, who leads Canada's most populous province and its largest economy, has been a vocal critic of the US tariffs.
Ontario has been among the Canadian provinces hardest hit by the US tariffs, particularly in the car and steel industries.
Mark Carney and Doug Ford have not yet commented on Trump's announcement.
The advert was run as part of a campaign worth $75m Canadian dollars (£40m; $54m) on mainstream TV channels in the US.
