The officials said Canada would be overwhelmed by the US in key military locations within two days to a week.

They said a US military attack is unlikely but the federal government is preparing for the worst-case scenario of an invasion.

General Jennie Carignan, Canada’s chief of defense staff, is on record as saying she wants to create a 400,000-reserve volunteer force.

The officials said Canada would expect nuclear-armed countries like France and Britain to come to the aid of Canada in case of an invasion. All three are NATO members, as is the US.

“You know if you come after Canada, you are going to have the world coming after you, even more than Greenland,” retired Major-General David Fraser, who led Canadian troops in Afghanistan, told a newspaper.

“People do care about what happens to Canada, unlike Venezuela,” he added.

“You could actually see German ships and British planes in Canada to reinforce the country’s sovereignty.”