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President Donald Trump said he had ended trade talks with Canada in retaliation for an anti-tariff advertising campaign launched by the province of Ontario, triggering a new commercial crisis with America’s northern neighbour.

The US president announced the move on Thursday night in a Truth Social post, complaining that ads aired in the US included the voice of former Republican president Ronald Reagan “speaking negatively about tariffs”.

“TARIFFS ARE VERY IMPORTANT TO THE NATIONAL SECURITY, AND ECONOMY, OF THE USA,” Trump wrote. “Based on their egregious behaviour, ALL TRADE NEGOTIATIONS WITH CANADA ARE HEREBY TERMINATED.”

Trump’s move threatens an abrupt rupture in his relationship with Mark Carney, the Canadian prime minister, who had steadied ties with the White House in recent months.

But Ontario’s premier Doug Ford, who has been an outspoken critic of Trump’s tariffs, has been championing the ads, which feature a radio address from former US president Ronald Reagan in 1987, where he describes such levies as detrimental in the long term.

A spokesperson for the prime minister’s office and Ford’s office declined to comment.

Carney this month flew to Washington to meet Trump in the White House in an effort to mend fractious bilateral relations and rescue a C$1.3tn ($928bn) trading relationship.

Trump has imposed 35 per cent tariffs on Canadian goods excluded from the US, Mexico and Canada free trade agreement. The US president also put duties of up to 50 per cent on steel and aluminium as well as anti-dumping levies and tariffs on softwood lumber.

Ford launched the television advertising campaign in the US targeting Republican voters this month.

“I’m a big Ronald Reagan fan,” Ford said last week, adding that he wanted to take the former president’s words on tariffs “and blast it to the American people”.

But the move triggered Trump’s fury. “They only did this to interfere with the decision of the Supreme Court, and other courts,” the US president said in the Truth Social post.

It referred to a case before America’s highest federal court on the legality of Trump’s levies on imports, based on emergency economic powers this year.

“The president is thin-skinned, we know this. But I thought the tone of the ads were civil,” said Flavio Volpe, the president of the Automotive Parts Manufacturers’ Association and member of the Canada-U.S. Relations Council.

Canada’s Ontario-based automotive industry, which has also been hit by tariffs, is facing closures and major job losses after Trump called for the repatriation of US carmakers.

The breakdown in trade talks between the US and Canada comes ahead of Trump’s trip to Asia, where he will attempt to defuse a flare-up in tensions with China during a planned meeting with President Xi Jinping.

On Wednesday night, Carney, during a televised address to the nation, unveiled plans to double Canadian exports to markets outside the US by 2035. “We won’t transform our economy easily or in a few months, it will take some sacrifices and it will take some time,” he said.

In a statement posted on X, the Ronald Reagan Presidential Foundation, said the Ontario ad “misrepresents” Reagan’s audio address, and complained that the province did not “seek nor receive permission” to use the remarks. The organisation added that it was “reviewing its legal options in this matter”.