they either lean on NATO or Commonwealth allies, or build them internally.
there is no other way to resist US military power
economically Canada does not have enough good ports and transportation options to get the same volume of good to China or EU as it does into the US.
It's also a deterrence.
I'm struggling with how to articulate the idea that seems to be in so many Canadian heads, regardless of their military experience.
Assume the worst case, that the US invades Canada and that no allies come to assist, for whatever reason.
The best the US can hope for is a pyrrhic victory: while it may well be true that the Canadian military and population cannot hope to resist the US military, anyone thinking there would be anything other than a pyrrhic victory does not understand how, uh, what words to choose, hmm, bloody mindedly petty and vindictive Canadians can be.
There is that old trope about mistaking "polite" for "nice". Canadians are mostly are the former, and are mostly the latter most of the time, and can even be the former while not at all being the latter. But remember too the trope as to why so many of the specific rules of the Geneva Convention, etm., exist.
Canadians don't pick fights, generally, but see fights to the end, always, and almost always no matter what. And it's not a red mist thing: That comes and clears. What is left is cold. Sober. Focused. Are you still here? Are you not retreating fast enough? Do I still have functional limbs/weapons/comms? Carrying on....
We don't stop until it is safe to stop, and by safe I mean we can stand down and not have to stand to again, or until there is no we left.
Now, more tropes:
Longest sniper kill: Canada has the top spot and at least two more of the top five. Those are all recent.
Only force to meet its D-Day objectives: Canada, with fighting as fierce on Juno as elsewhere.
Only western soldier to fire on a Soviet: A Canadian with the group sent to protect Denmark from Soviets who were rolling fast and hard over northern Germany. The RoE were sort of vague on that point, but they were explicit about not withdrawing, about not giving up an inch. Words didn't work, triggers were pulled, a standoff occurred until sufficient forces arrived to convince the Soviets to withdraw to their agreed lines.
Before becoming PM, Lester B. Pearson won the Noble Peace Prize for the idea of UN Peacekeepers, of putting Canadians in harm's way to separate combatants in hot zones. The idea was taken seriously because memories of Canadian performance in WWII and Korea were fresh in mind. "Oh, those guys? Yeah, OK, ceasefire and separation sounds good."
Again, I am not in anyway suggesting that the US would not win in an invasion of Canada, if Canada stood alone. What I am suggesting is that what would be left (of the US, let alone Canada) would make the victory hollow and bitter.
(You do know that the Canadian boycotts that are so impacting tourism and distillers, among others, are not economically motivated, right? So many US talking heads cite tit-for-tat tariff nonsense, and very few miss the point entirely: Canadians mostly didn't give a damn about tariffs, but when "51st state" was mooted, even if as a joke, Canadians stopped buying US stuff. The tariffs could disappear today and many would still push for closer ties with the EU, possibly even membership, for distancing Canada from the US even more, all because we are fiercely independent, and willing to sacrifice a great deal to retain that independence. Canadians are mostly quiet about it, but never mistake silence for acquiescence or consent.)
The (over) emphasis on north south came a bit later. And certainly since the signing of the FTA it's been the most important thing.
Shipping to China from ports in Vancouver and to Europe from ports in the gulf of St Lawrence is actually quite strategically advantageous.
It's on us to push to develop this more.