“This is not a joke anymore,” Joly told Newsnight. “There’s a reason why Canadians, when they go out on a hockey game, are booing the American national anthem… We’re insulted. We’re mad. We’re angry.”

Her comments come after Trump imposed 25% tariffs on products entering the US from Canada on Tuesday. Canada’s Prime Minister Justin Trudeau called that a “very dumb thing to do” and announced retaliatory tariffs.

However, US Commerce Secretary Howard Lutnick said Trump would “probably” announce a deal to reduce tariffs on Wednesday.

In response, Joly told the BBC that “at the end of the day, the only one that really takes a decision is President Trump”.

She said no Trump administration secretaries had contacted their Canadian counterparts on Monday or Tuesday about tariffs

Trump announced 25% tariffs on Canada and Mexico on 4 February, but delayed implementation until 4 March. Canadian energy imports face a 10% tariff.

Ontario Premier Doug Ford implemented a 25% surcharge on electricity exports to three US states, and if tariffs escalated, said he would consider cutting Michigan, New York and Minnesota off from Canadian power.

Trump also imposed a 10% tariff on goods worth more than $800 (£645) from China in February, which doubled in March. China responded with its own tariffs.

The White House said when it introduced the tariffs that it was “taking bold action to hold [the three countries] accountable to their promises of halting illegal immigration and stopping poisonous fentanyl and other drugs from flowing into our country”.

Fentanyl is linked to tens of thousands of overdose deaths in the US each year.

Trudeau said his country was responsible for less than 1% of fentanyl entering the US.

Canada had introduced new border security measures in December, in response to Trump’s tariff threats before he took office.

“We didn’t want this trade war. We did everything that was required under the executive order to make sure our border was safe and secure,” Joly told the BBC, but said “this is a bogus excuse on the part of the Trump administration against us”

Joly said Canada was the “canary in the coal mine”, with the Europeans next, and the UK after that. Trump has threatened 25% tariffs on the European Union as well.

She said Canada and the UK should work together: “That’s also why I went to London to make sure that if there are tariffs imposed, we should work on counter-tariffs well.”

Joly said Canada’s public displays of displeasure against the US are not “against the American people. We’re the best friends of the American people”.

She called the tariffs on the US’s biggest trading partner an “existential threat”.

“We cannot let our guard down,” she said. “We need to make sure that we fight back.”