The modelling provides the keenest insight yet as to the level of threat assessment now being actively discussed by Canada with respect to the Trump administration.
One of the officials noted, however, that relations with the U.S. military remain positive and the two countries are working together on Canada’s participation in a new continental defence system, or “Golden Dome,” to defend against Russian or Chinese missiles.
The military has also run models on missile strikes from Russia or China on Canadian cities and critical infrastructure.
Military planners envision an American attack that would follow clear signs from the U.S. military that the two countries’ partnership in NORAD, the North American Aerospace Defence Command, was ending, and the U.S. was under new orders to take Canada by force.
Conscription has been ruled out for now, but the level of sacrifice that would be asked of Canadians remains a central topic, the officials said. General Jennie Carignan, Chief of the Defence Staff, has already announced her intention to create a 400,000-plus-strong reserve force of volunteers. The officials said they could be armed or asked to provide disruptions if the U.S. becomes an occupying power.
A senior Defence Department official said Canada would have a maximum of three months to prepare for a land and sea invasion. The first indications that invasion orders had been sent would be expected to come from U.S. military warnings that Canada no longer has a shared skies policy with the United States, the source said.
This rupture in the joint defence agreement would likely see France or Britain, nuclear-weapon states, being called on to provide support and defence for Canada against the U.S.
The Globe is not identifying the senior defence official, who was not authorized to discuss Canadian war-modelling scenarios.
Retired major-general David Fraser, who commanded Canadian troops in Afghanistan alongside the United States, said Canada could also use drones and tank-killing weapons like the Ukrainians used against the Russians to blunt their invasion in February, 2022.
Mr. Fraser said it is unthinkable that Canadian planners have had to draw up a U.S. invasion scenario. Whatever Mr. Trump does with Greenland and possibly Mexico would weigh into any Canadian scenario, he said.
But Canada can count on support from European countries, Britain, Japan, South Korea and other democratic nations.
“You know if you come after Canada, you are going to have the world coming after you, even more than Greenland. People do care about what happens to Canada, unlike Venezuela,” Mr. Fraser said. “You could actually see German ships and British planes in Canada to reinforce the country’s sovereignty.”
Mr. Fraser said Canada should immediately place more military assets in the North to claim its right to the region.
If the threat from the U.S. became serious, he said Canadian soldiers would be placed along the border even though there is no realistic possibility that Canada could defeat the U.S. militarily.
Insurgency tactics would be the best way to deal with U.S. invading forces, he said.
“There is a quantum difference between defending another land like Canadians did in Afghanistan versus defending Windsor, Ontario. You do not walk across that border because everybody is your enemy then,” Mr. Fraser added.
Retired lieutenant-general Mike Day, who headed Canadian Special Forces Command and served as chief strategic planner for the future of the Canadian Armed Forces, said it was “fanciful” to think the Americans would actually invade Canada.
But he acknowledged Canada’s armed forces could not stand up to the world’s biggest and most sophisticated military. He said, however, that the U.S. would have great difficulty occupying a country the size of Canada.
“We wouldn’t be able to withstand a conventional invasion. We would, for a limited period of time, be able to defend a very small civilian population, like the size of Kingston,” he said.
“Notwithstanding the size of the American military, however, they do not have the force structure to occupy, let alone control every major urban centre in Canada.”
“Their only hope would be a Russian-like drive to Kyiv and hope that works and the rest of country capitulates once they seize the seat of power in Ottawa,” he added. “Like Ukraine, it would inconceivable to me that we would give up if they seized our capital.”
Gaëlle Rivard Piché, executive director of the Conference of Defence Associations, said she did not see a situation where the U.S. would attack Canada. But she also said it’s crucial for Canada to significantly build up its defence capabilities.
“Clear signalling to our neighbour to the south that we want and we’re willing and able to rapidly be a credible ally that is capable of defending itself, ensuring our own national security, our national defence, will play a deterrence role towards a potential willingness by the United States to control some of Canada or to invade a portion of Canada,” she said.
University of Toronto political scientist Aisha Ahmad said Canada needs to drastically boost its homeland defence capabilities, regardless of the potential U.S. threat to the border.
“The better Canada can embrace this approach to homeland defence, the less likely all of these horrible scenarios that nobody wants will ever come to pass,” she said.
U.S. generals would be aware that Canadians would fight back against an invasion, using whatever tactics would be the most effective, she said.
“I do believe that there are intelligent generals south of our border who could very easily identify that risk environment.”
