I highly doubt there would be much of a civilian resistance when access to arms and ammunition is nearly non existent. It's one thing to say "hell ya I'll fight those bloody yanks!", it's another to form civilian defense forces with absolutely no weapons vs armor and basic infantry. The CAF itself has shortages of bullets, so where am I supposed to go to get a rifle locally? Walmart?
Afghanistan and Iraq were a potent laboratory for what works in the modern context, and Ukraine has added a generational leap in technology. Direct fire small arms engagements generally aren’t it. The other guy pretty much always loses those. Effective attacks in the war we were in were usually IEDs. Now we’ve also had Ukraine show us the potency of FPV drones, granted we generally only see the minority of strikes that work.
The United States doesn’t leave wars because it has been militarily defeated. It leaves wars when the political appetite wanes, generally due to the cost in blood and treasure. The war doesn’t need to be won by the resisting power; they simply need to make it not worth it.
While I remain confident that a U.S. military incursion i to Canada is exceptionally unlikely, pondering the realities of it are still interesting. Such a venture would only make sense if done for long term, large scale economic reasons. Necessarily that would mean cross border trade would have to continue; you can’t plunder if you don’t bring wealth back home. A third of a trillion dollars in goods exports to Canada a year mean lots of trucks and trains will still cross the border north. That means things can come in- weapons, tools and good to make or be converted into weapons… Canada would likely get a lot of material help from south of the border. We can’t keep US guns from crossing north even now when we
want to. Imagine that suddenly reversing. For those really inclined to arm themselves, I imagine there are a lot of semiautomatic rifles surprisingly well preserved and easily findable at the bottom of lakes where the boat tipped over.
There is
all kinds of nuisance, inconvenience, and expense that could be inflicted on America. How easy would it be to close the St Lawrence seaway? Or to choke off any of the narrow bits in the Great Lakes? You don’t need to sink ships; just start flying drones into the bridge to maim the crews and render them uninsurable. To a lesser extent the approaches to the port of Seattle could be similarly threatened- or at least made into a burdensome security operation. Oil and gas pipelines? Forget about it. Same with any land travel to and from Alaska. Puppet government and collaborators? They’d get taken out easily enough.
Safe bet that at least a few people within the Canadian intelligence apparatus would be in a position to massively and irreparably compromise America’s SIGINT collection and cyber operations against foreign adversaries. Simply letting foreign adversaries know what sort of stuff has been collected, what’s been getting listened to- it would be a decade rebuilding that. Lots of potential injurious compromise of other military capabilities too. An invaded Canada would no longer have any motivation to keep America’s secrets.
A lot of Canadians would die of course. As we know from previous conflicts, fighting a partially urbanized counterinsurgency means killing a lot of people. We also know that doing so fuels hatred and radicalization. The number of Canadians motivated to resist in ways small and large would only increase with time and casualties.
Anyway, that’s all just thinking out loud, and this is just the dumb ramblings of a guy who was a part time infantry NCO, went to the sandbox once, and then became a cop. A lot of people are way smarter than me, way more devious, and would be way less inclined to abide by anything resembling civilized rules.
So I don’t think we’ll actually see a U.S. invasion of Canada. Not because they couldn’t succesfully do so - of course they could - but because the return on investment would be dismal.
