A Canadian state wants to swamp US TV networks with a commercial showing Ronald Reagan opposing tariffs. Trump says that’s an attempt to influence US courts.

An advertisement released in the United States by Canada’s biggest province featuring former US President Ronald Reagan has set off new tensions between Washington and Ottawa, which already had icy relations over President Donald Trump’s tariff policy.

In a post on Truth Social on Thursday night, Trump claimed that the advertisement – which shows Reagan, a fellow Republican, speaking negatively about tariffs as an economic policy – was “fake”. He cited comments by the Ronald Reagan Foundation that described the clip of the former president used in the commercial as doctored.

Trump also said the advertisement was aimed at influencing US courts.

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

Why is the advertisement creating tensions between the US and Canada? Here’s what we know:

What was the advertisement aired by Ontario?

On October 14, Doug Ford, the premier of Ontario, said his province would spend 75 million Canadian dollars (US$54m) to run anti-tariff advertisements on mainstream channels in the US.

Ford has been a critic of Trump’s tariff policy, and Ontario, known for its steel industry, has been severely hit by the US levies. Ontario is home to more than a third of Canada’s population and the country’s biggest city, Toronto.

On October 16, Ford posted the ad on his X account and said Canada will “never stop making the ca