You make good points, but my point wasn't that Russia would use a beachhead in the arctic, but that it can use flight paths through the arctic to project power

You make good points, but my point wasn't that Russia would use a beachhead in the arctic, but that it can use flight paths through the arctic to project power in southern Canada. long-range missiles are one thing, but strategic long-range bombers with some in-flight refueling too. As far as an actual invading force, that I concede, they can't do that today, but who knows what they're planning, they have the manpower, the money and the lunacy to build up such a force. Their main advantage is the nuclear deterrent preventing others from invading them back. Canada has been left alone so far (by everyone hostile) because it has (had?) the US's protection, not because of it's fearsome military (although I know they're quite fierce on their own -- just not B52, nukes, ICBMs, aircraft carriers level fierce). If I had to speculate, they won't try to take populated centers of Canada, but they might make claims to arctic resources and land, and just take it. Start bombing Toronto and Montreal if Canada fights back. They might even do it in the next few years if the US starts enough chaos elsewhere as a distraction. Once they take land, you're not getting it back, why? Back to my original point: They have nukes.