Canada is bracing for a possibility its own government and military officials still consider unlikely: military action by the United States.

Last week, in an interview with The New York Times, Prime Minister Mark Carney said his government had considered the possibility of U.S. military action against Canada as an "extreme tail risk.”

Carney said that his government did not expect an American invasion. “But it would be irresponsible for Canadian leaders not to consider even very improbable eventualities as the relationship between the two countries shifts,” he said.

Carney said, “That’s just risk management.”

The issue has been a rising focus of attention during President Donald Trump’s second term. Trump has repeatedly spoken of the prospect of Canada becoming the 51st U.S. state and said in January 2025 he would not use military force to achieve that goal but economic pressure.

But the rhetoric has still affected the way some Canadians view their country's security relationship with its southern neighbor.

A Leger poll in January found 31 percent of Canadians believed the United States would likely use “direct action” to seize Canada. The survey was conducted online with 1,540 Canadians between January 9 and January 11, after the U.S. military intervention in Venezuela.

But the Pentagon says a conventional U.S. invasion is still highly unlikely.

Why an invasion is still unlikely

Canada and the United States have spent decades building one of the most integrated defense relationships in the world.

Both are NATO members and work closely together in the North American Aerospace Defense Command, or NORAD. Their militaries cooperate in joint operations and exercises, and the two governments regularly share intelligence.

In his military career, an attack from U.S. territory was never considered a realistic scenario, said Lt.-Gen. Christopher Coates, a retired senior Royal Canadian Air Force officer.

The history of the two countries does not lend itself comfortably to the notion of conventional war between them given the existing security architecture.

That also means any deterioration in relations would not necessarily start with tanks rolling over the border. Cyberattacks, economic pressure, intelligence operations, or other means of coercion could be more pressing concerns.

Canada has worried about U.S. power before.

Canada and the United States are now close allies and deeply integrated economies, but their relationship has not always been so cooperative.

Fear of American expansion was a major factor in the political development of British North America.

U.S. forces also attacked British North American territory during the American Revolutionary War, including an unsuccessful attempt to take Quebec City. American forces once again invaded the British North American colonies during the War of 1812.

Neither side achieved a decisive territorial victory in the conflict. In 1814, British troops and their allies invaded Washington, D.C., setting fire to several government buildings, including the White House.

The experience of history helped to reinforce a long-standing Canadian anxiety about the military and economic power of the neighbor.

After the First World War, Canadian military planners revived that concern by contemplating the possibility of a future conflict with the United States. Historical research has documented Canadian efforts to gather intelligence concerning American infrastructure and transportation routes.

Military planners routinely game out scenarios that might never happen. The goal is not necessarily to predict conflict but to understand vulnerabilities and possible responses.

What Canada has really modelled

The distinction matters to the current discussion.

Earlier this year, The Globe and Mail reported that the Canadian Armed Forces had come up with a hypothetical U.S. invasion and thought through how Canada would respond.

The exercise was said to have concluded that Canada’s smaller military could not compete with U.S. forces in a conventional war. Thus the modelling considered unconventional forms of resistance, such as ambushes, sabotage, and hit-and-run attacks.

But it should not be interpreted as a detailed Canadian war plan for an imminent American attack.

The Globe and Mail noted the work was **a conceptual military model, rather than an operational, step-by-step plan.**

That distinction matters, because military organizations routinely study hypothetical threats, including threats that policymakers do not expect to materialize.

The Military Imbalance

And the military imbalance between the two countries is stark.

Canada’s military has an “authorized strength” of 71,500 Regular Force members and 30,000 Primary Reserve members. As of 31 March 2026, the Canadian Armed Forces had some 67,800 Regular Force members and 25,100 Primary Reserve members.

But Canada continues to grow its defense capacity. The government has increased defense spending, met NATO’s 2% spending target, and announced new investments in aircraft, missiles, cyber capabilities, and Arctic defense.

The government is also looking at a major expansion of its supplementary reserve. Defense officials have said that 300,000 is an aspirational goal, not a plan to create 300,000 lightly trained soldiers today. Participation would be voluntary, and the proposal is still being developed.

Why it matters in a non-invasion scenario

The importance of Canada's planning, then, may lie less in the probability of an American attack than in the manner in which Ottawa is rethinking its reliance on the United States.

Canada is seeking to establish greater strategic autonomy, including through diversifying defense, technology, and supply-chain relationships, Carney said. His government has also announced new defense partnerships with European countries and more money for Canadian military capabilities.

The changes reflect a larger worry: For decades, Canada’s security strategy has rested on close cooperation with the United States. A more erratic relationship with Washington forces Canadian policymakers to consider what happens if that assumption becomes less reliable.

That doesn't mean Ottawa expects American troops to cross the border.

It means Canadian officials are no longer willing to treat the possibility as one that need not be considered.

This is a significant shift in strategic thinking for a nation that has long relied on its closest neighbor to also be its closest ally.