Why Canada is preparing for a (long shot) US invasion

Why Canada is getting ready for a (long shot) US invasion

Prime Minister Mark Carney acknowledged last week that he has been preparing for a once-unthinkable possibility: a US invasion.

He said the risk was low and the odds highly improbable, but told the New York Times he had a duty to weigh every scenario as the US-Canada relationship is being reshaped under the Donald Trump presidency.

"That's just risk management," Carney said.

Trump’s global tariffs and his repeated wish to make Canada the 51st state have prompted Canada to war game an American attack.

In 2025, the US president said it was "highly unlikely" the US would ever use force against Canada. Instead, he said, he would keep applying economic pressure to achieve political goals.

"President Trump has done more than anyone to protect the great people of Canada," the White House told the BBC in a statement this week.

Military experts who spoke to the BBC also view an invasion as a long shot, citing the many ways the two countries cooperate on defence.

Still, the issue is clearly on Canadians’ minds.

In January, after the US captured Nicolás Maduro in Venezuela, a Leger poll suggested that more than 30% of Canadians believed a US invasion was likely.

A war between Canada and the US would be complicated and almost impossible to imagine, said Lt-Gen Christopher Coates, a former Royal Canadian Air Force officer of 34 years who held several senior posts.

"I was involved in military operations for my whole career, and we never considered the possibility that there would be a military attack coming from US territory," he told the BBC.

Coates, who served on Nato missions, said Canada and the US work together on many areas of military defence.

Both are members of the north Atlantic defence alliance, which requires members to defend another member nation if it is attacked.

The two countries also carry out joint Arctic defence missions under the North American Aerospace Defence Command (NORAD), and they often exchange intelligence.

Because of that, Coates said he believes any US attack on Canada would not start with a conventional armed assault, but with quieter methods such as cyberwarfare.

After World War II, Canada and the US became natural allies for the latter part of the 20th Century, and grew deeply integrated economically, militarily and culturally.

But that was not always the case. In fact, a central part of Canada’s identity is its resistance to US expansionism in the 18th and 19th Centuries, said Tim Foran, a researcher at the Canadian War Museum.

"Fear of the United States is foundational to the political project that is Canada," he said.

Canada was created as a group of British North American colonies that stayed loyal to the British Crown when the colonies in what is now the US rebelled.

Before Canada was formed, the US had tried to invade British North American colonies, seizing Montreal in 1775 and nearly taking Quebec City.

During the war of 1812, Americans repeatedly invaded what were then Upper Canada, Lower Canada and the maritime colonies, ending in a stalemate. In that war, British troops famously burned down the White House in retaliation.

Foran said that at the time, the colonies that later became Canada depended on Great Britain and its Royal Navy for defence, as well as indigenous peoples who served as generals in major battles.

Canada again considered war with the US after World War I in response to America’s growing power and influence.

It drew up a plan shaped by secret trips to border cities made by Canadian army generals, who posed as tourists and took photos of bridges and highways for intelligence.

They also talked with local residents to better understand their enemy.

A war was an unlikely outcome then, said Andrew Burtch, a Canadian War Museum researcher with expertise on Canada in the 20th Century, but the Canadians still wanted to be ready.

"That's part of what militaries do," he said. "They envisage all sorts of different scenarios."

Canada-US relations have worsened under the second Trump presidency.

Even if a US invasion is extremely unlikely, Matthew Schmidt, an associate professor of national security at the University of New Haven in Connecticut, said the fact that Canadians are preparing shows how dramatically the global order has changed.

He added that Canadian leaders have difficult questions to answer about how closely they want to keep working with the American military — a partnership that gives them valuable information if they ever wanted to harm Canada in any way.

"It's really doing harm to relationships with the United States, and there's a certain amount of legitimate fear," he said.

Americans may not take Trump’s comments about making Canada the 51st state seriously, he said, but Canadians clearly do — and are ready to defend themselves if necessary.

So what would it look like if it happened?

The opening phase of a war could be very brief.

According to the model used by the Canadian military, as reported by the Globe and Mail newspaper earlier this year, a US attack would overwhelm Canada’s strategic positions within a week.

Its military would quickly be outnumbered, forcing Canadian forces to turn to guerilla-type warfare in an effort to suppress the enemy.

Allied countries such as France and Britain would be asked to support and defend Canada, the newspaper reported in January, citing senior government officials.

The theoretical model is thought to be the first time in a century that Canada has planned for an American assault.

Coates said the modelling is on the lighter end of military combat planning.

He said Canada, unlike its Nato allies, has been behind in having a response plan ready in the event of any ground invasion, and is now catching up in this era of unpredictable geopolitics.

Part of that, he said, was shown by a recent call from Canada’s defence chief to sharply expand the size of its military, including adding as many as 300,000 lightly trained citizen soldiers.

An invasion of Canada might not be simple from the US side either.

Even with its enormous military, the US would struggle to get support for a war with Canada, Schmidt said.

"I think you would have a large number of American officers who would resign if given the order to invade Canada," he said.

"They would see it as an illegal and immoral order."

Schmidt said Canadian and American soldiers regularly train together and share mutual respect.

But if relations ever deteriorated to the point of combat, Schmidt said the US would likely concentrate on seizing valuable Canadian resources such as oil and minerals, and on political decapitation.

"You would see a a kind of operation that would mirror perhaps what you saw in Venezuela," he said, referring to US military action earlier this year to capture former Venezuelan President Maduro.

Although he acknowledged that the US has greater military capacity, he said that "pound for pound" Canadian soldiers would be able to put up a fight.