What an awful analogy that misses any sort of context or nuance about the situation.

That's the problem with liberals like you, that you think things can be understood by imagining it as something superficially similar.

Do you understand what historical materialism is?

To be clear, to be a true analog the province needs to be an ethnic minority which is being targeted by the national government.

Say Alberta was the only majority English speaking province, and Ottawa started putting up statues of a Quebecois terrorist leader from 80 years ago who lead the massacre of 100k English speakers and allied with Hitler during WW2, then they announced that English would be banned from all government facilities including primary schools, and when Alberta tried to secede they sent Nazi paramilitary death squads to harass them and started bombing them daily.

At that point, if the US interceded and went past the Albertan border to attack other military targets in Canada, you would consider that a war of aggression by America against Canada and not them defending their ally, Alberta?

If I considered it justified for the US to enter the war on the side of the separatists, I would absolutely say that it is then justified for the US to invade Canada proper.