Oh and another thing I only discovered recently. You spoke of Natural Resources. The sorts of things that make greedy men's eye gleam.
In the 1930's, The USA, with whom as you know we here in the UK share a 'special relationship' had put together a plan for the destruction of the British Empire. They were terribly worried at our strangle hold on international trade. They got so far with the planning that airfields and military bases were set up, in secret, next to the Canadian border in readiness for invasion.
That was in the late thirties, before America became a world power. Don't believe me? Think I'm still a conspiracy theorist/crank/nutjob? Read this...
How America planned to destroy BRITAIN in 1930 with bombing raids and chemical weapons | Mail Online
Then wonder what would happen if, just after Christmas, the brown solids really hit the fan and the US suddenly needed what Canada had.