Prime Minister Mark Carney admitted last week that he has prepared for a once-unthinkable scenario: a US invasion. Noting that the risk was low and the likelihood highly improbable, he told the New York Times he had a responsibility to consider all possibilities as the US-Canada relationship is redefined under the Donald Trump presidency.
“"That's just risk management," Carney said.
Trump's global tariffs and his often-repeated desire to make Canada the 51st state have led Canada to war game an attack by the Americans. In 2025, the US president stated it was "highly unlikely" that the US would ever use force against Canada. Instead, he indicated he would continue to exert economic pressures to obtain political aims.
“"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 think an invasion is a long shot, pointing to the multiple ways the two countries work together on defence. However, the issue is clearly weighing on Canadians' minds. In January, after the US captured Nicolás Maduro in Venezuela, a Leger poll suggested that over 30% of Canadians believed that a US invasion was likely.
Historical Context
A war between Canada and the US would be complicated and almost difficult to imagine, said Lt-Gen Christopher Coates, a former military officer of 34 years with the Royal Canadian Air Force who held various senior positions.
“"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 had served on NATO missions, noted that Canada and the US collaborate on many aspects of military defence. They are both members of the North Atlantic defence alliance, which mandates members to defend a fellow member-nation should they be attacked. The two countries also conduct joint Arctic defence missions under the North American Aerospace Defence Command (NORAD) and frequently share intelligence.
Because of this, Coates believes an attack by the US on Canada would not begin with an armed assault, but rather with more discreet means like cyberwarfare.
Canada-US Relations
After World War II, Canada and the US became natural allies for the latter part of the 20th Century, heavily integrating economically, militarily, and culturally. However, it wasn't always this way. A core tenet of Canada's identity is its resistance to US expansionism in the 18th and 19th Centuries, said Tim Foran, a researcher with the Canadian War Museum.
“"Fear of the United States is foundational to the political project that is Canada," he said.
Canada was formed as a collection of British North American colonies that remained loyal to the British Crown when the colonies in modern-day US rebelled. Before the formation of Canada, the US had attempted to invade British North American colonies, taking control of Montreal in 1775 and nearly conquering Quebec City. In the War of 1812, the Americans invaded what was known then as Upper Canada, Lower Canada, and the maritime colonies repeatedly, resulting in a stalemate. During that war, British troops famously burned down the White House in retaliation.
