US President Donald Trump has announced an immediate end to all trade negotiations with Canada over an advert critical of the tariffs he has imposed on the nation.

The advert, sponsored by the government of Canada's province of Ontario, quoted Trump's predecessor, Ronald Reagan, an icon of US conservatism, saying tariffs "hurt every American".

Trump wrote on social media that the advert was "FAKE" and "egregious", adding that trade talks were "HEREBY TERMINATED".

His administration has imposed a 35% levy on many Canadian imports, as well as individual tariffs targeting particular industries like car and steel manufacturing. Ontario has been particularly hard-hit by these.

Trump has allowed exemptions for goods that fall under a free trade agreement with Mexico and Canada that he negotiated during his first term.

But Canada's Prime Minister Mark Carney has since his election earlier this year attempted to strike a deal that would ease the US tariffs.

This has been complicated by Ontario Premier Doug Ford, who is one of the most vocal critics of the taxes levied on US firms buying Canadian products.

In the minute-long advert published last week, Reagan's voice can be 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.

"When someone says 'let's impose tariffs on foreign imports', it looks like they're doing the patriotic thing by protecting American products and jobs. And sometimes, for a short while it works, but only for a short time," Reagan says in the advert.

"But over the long run, such trade barriers hurt every American, worker and consumer.

"High tariffs inevitably lead to retaliation by foreign countries and the triggering of fierce trade wars... Markets shrink and collapse, businesses and industries shut down and millions of people lose their jobs."

The Ronald Reagan Foundation - which is charged with preserving his legacy - released a statement on Thursday saying the advert had used "selective" audio and video of the former president's remarks.

It said the advert "misrepresents" the former president's address, without specifying why, and accused the Ontario government of not seeking permission to use and edit the remarks.

The foundation said it was "reviewing its legal options".

Trump referenced this statement, and said the video was designed to "interfere with" the US Supreme Court's upcoming decision in November on whether Washington's sweeping tariffs on many nations' products 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.

While the minute-long advert only includes excerpts from the original, five-minute-long address, it does not alter Reagan's words.

The order in which he makes the comments has been changed. The advert's penultimate sentence is taken from near the beginning of his speech, and a phrase that features about halfway through the advert is likewise taken from an earlier point in the address.

The original address - titled Address to the Nation on Free and Fair Trade - is regarding a specific set of tariffs the Reagan administration had at the time imposed on some Japanese goods.

Reagan seeks to use the speech explain why he had introduced the tariffs in this "special case" despite his belief that "imposing such tariffs or trade barriers and restrictions of any kind are steps that I am loath to take".

He makes clear that he wants to lift them as soon as possible "to promote the prosperity and economic development that only free trade can bring" - a position he stresses throughout the speech.

The advert was run as part of a campaign worth $75m Canadian dollars (?40m; $54m) on mainstream TV channels in the US.

In a post accompanying the advert, Ford wrote that "we'll never stop making the case against American tariffs on Canada".

China's embassy in Washington also used a similar Reagan clip in a post on X to cast doubt on Trump's global tariffs earlier this year.

Ontario is Canada's most populous province and its largest regional economy, and has suffered the most as a result of the US tariffs.

Ford hit back at Trump's earlier tariff threat against Canada by saying he was willing to cut off power supply to the US.

He had also described Washington's trade policies against Canada as having pulled a knife and "yanked it into us", and called on US lawmakers to put pressure on Trump.

Trump's sector-specific levies on Canadian goods include a 50% levy on metals and 25% on automobiles.

The White House's global tariffs - particularly on steel, aluminium and cars - have hit Canada hard, forcing job losses and putting pressure on businesses.

Carney and Ford have not yet commented on Trump's announcement.

It is the second time Trump has said he was ceasing trade talks with Canada, after Ottawa announced it would impose a digital services tax on US technology firms earlier this year.

When Canada rescinded the tax, the White House said Carney had "caved" to pressure from Trump. (BBC)

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