> I don't know. Americans were fine claiming the "high ground" the last time a bunch of states and territories tried to secede and forced back into the union with military force.
Slavery.
Americans also like to make every historic victory sound like the entire conflict was about moral ideals and they were the flawless defenders of the Right Thing.
Interestingly the way people outside the US are taught about the American Civil War is far more nuanced: state rights, economical reasons, sovereignty, etc.
But I guess "the North declared war on the seceding South because the South was literally worse than Hitler" is a valid interpretation too. Teach the controversy, right?
The thing people forget when talking about secession is that unless the constitution was explicitly written to make affordances for future secessions, every attempt at secession is illegal and can be considered an act of civil war.
Aside from "voting irregularities" one of the major talking points when the Crimean peninsula voted to secede from Ukraine and be annexed into Russia was that there was no legal basis for them to do this, even if the elections had been undisputed.