Canadian Prime Minister Mark Carney says he has examined the possibility of a US military attack against Canada, according to The New York Times.

In an interview with the newspaper on Wednesday, Carney described an attack as an “extreme tail risk” – an event with a very low probability but potentially severe consequences.

“That’s just risk management,” said Carney, the former head of the Bank of England. “It would be irresponsible not to.”

Experts say his comments do not indicate that a war is likely or that Canada is preparing to fight one, but they do show that Carney considers it a remote possibility. Here is what that might mean.

Why are relations between Canada and the US strained?

The main bones of contention are the ongoing trade war and Trump’s jibes about Canada becoming a US state.

Trade war

Shortly after Trump returned to the White House in 2025, he imposed a 25 percent tariff on goods imported from both Canada and Mexico, saying they would not be lifted until both countries took steps to curb the flow of fentanyl, a highly addictive and lethal drug, into the US. The leaders of Mexico and Canada struck a deal pausing the impending tariffs for 30 days, but they were reimposed on Canada in early March after Trump declared that it had failed to do enough.

In July 2025, he threatened to raise that to 35 percent unless Canada backed down on a digital services tax, which it agreed to do.

Canada, the biggest foreign supplier of steel and aluminium to the US, was also badly hit by Trump’s separate 25 percent tariffs on steel and aluminium, which he imposed globally in March 2025.

Since last year, trade talks have continued but ultimately collapsed in August, and both sides have since imposed new, tit-for-tat tariffs. Trump levied 50 percent taxes on $20bn of Canadian goods, and Canada matched them for US goods.

The problem for Canada is that its economy is closely tied to that of the US, making a trade war particularly consequential. Some 72 percent of Canada’s $556bn goods exports went to the US in 2025.

Security threat

Trump has made much of this dependence. “I think Canada would be much better off being a 51st state,” the US president said in 2025.

When trade talks fell apart this year, Trump responded to Carney’s announcement by writing on his platform Truth Social: “Canada wants the benefits of being a State, without being one!!!”

Trump also took the provocative step of renaming Lake Ontario – which sits along the border of Canada and the US – “Lake America”.

Carney is, therefore, seeking to reduce that dependence. His government is also reviewing its planned purchase of American F-35 fighter jets, while Carney said that Canada also intends to rely less on SpaceX’s Starlink satellite internet service.

This month, he has visited the European Union and the United Kingdom in a bid to expand alliances. The EU has offered associate membership to Canada, while Canada has applied to join the UK-led Joint Expeditionary Force (JEF), a European military coalition.

Ty Solomon, a professor of international relations at the University of Glasgow, told Al Jazeera there were “at least two issues at play” when it came to tensions with the US. The first was “the hostility that President Trump has shown towards Canada”, reflected in his threats to annex it as the “51st state”, and the tariffs both countries have imposed.

The second, Solomon said, was a changing security landscape that included US threats last year to annex Greenland, as well as “ongoing Russian and Chinese interest and activity in the Arctic”. In this “multifaceted geopolitical environment”, he said, “unexpected events in one area could trigger further unexpected dynamics in these other areas”.

Therefore, while US military action is a “vanishingly small possibility”, Eric Taylor Woods, an associate professor of political communication at the University of Leeds, told Al Jazeera that Canadians are nevertheless unsettled by Trump’s comments and want to know their prime minister is defending the country’s sovereignty.

Carney set out this new geopolitical reality at the World Economic Forum in January, when he urged countries such as Canada to work together as great powers use their influence more aggressively.

“If we’re not at the table, we’re on the menu,” he said.

What would happen in a military conflict between the US and Canada?

Experts consider a US attack on Canada highly unlikely – Solomon said a US attack on Canada remained “somewhat unthinkable”.

But, Woods said, if there was one, “I would not expect Canadians simply to accept the loss of their sovereignty”, despite the “enormous disparity in military capabilities”.

“The US has a vastly larger and more powerful military than Canada,” Solomon said. “On paper, then, there would appear to be no contest.”

But, he said, the prolonged US war against Iran had cast doubt on assumptions about “overwhelming US military force and effectiveness”.

Furthermore, Solomon said, if it did happen, it would be “an unmitigated disaster for American global interests”.

“What remaining trust there is of the US would evaporate completely, and it would greatly accelerate other democracies’ efforts to forge new alliances outside of the American security and alliance system,” he added.

What happens next?

The unease between the two is likely to continue.

Carney has said he is still prepared to reach a trading deal with Trump. He told The New York Times that they had spoken “frequently” since trade talks collapsed. “We can pick up the phone and talk to each other about issues,” he said. “He’s direct. I’m direct.”

Woods noted, also, that Trump had so far avoided the “schoolyard personal insults and name-calling” he often directed at Carney’s predecessor, Justin Trudeau.

Solomon said that “privately, I suspect that Carney and his advisers do not trust the Trump administration much at all: Trump is well known to change his mind – and American foreign policy – very quickly and seemingly on a whim”.

“As a leader, it is very difficult to trust this sort of behaviour because every agreement is built upon uncertain foundations.”