A lot of these hypotheticals can be answered by "we'll just slaughter anyone who makes a fuss" because that's where our country's moral framework will be if we ever march troops across the border. Like an ultra nationalist fascist state is going to concern itself with old treaties and popular sentiments.
From a Canadian prespective, we would commit all the war crimes we could against an invading force, especially one we could not fight a conventional war against and win.
Im talking sending American GIs home in unrecognizable condition.
I dont care what government is in power by then. Invade Canada and be prepared to die in horrible ways, mutilated, and sent back to your loved ones in chunks.
This is the only way we could win a war against the US and we would not hesitate to do it.
Realistically, we are so fucked. One single bomb on a highway or railway can completely decimate any one of our province's ability to move people or goods and perform services. Our border is too long and wild to be defendable. And they could probably take out our entire military logistics in a single night of bombings. All of this isn't even to mention that if they wanted to go all out insane they could make nuclear threats if the Canadian government doesn’t capitulate. I'm not saying we couldn't resist once occupied, it's just fucking hideous to think about.