You're sort of right. What the US is doing in Canada right now is more comparable to what Russia was doing in Ukraine in the early 2010s[0]

The upcoming Alberta separatist referendum that is funded and boosted by foreign agitators isn't intended to succeed. It's intended to cause a festering wound in Canada to prevent it from growing in strength and independence from America.

As far as I'm concerned America has already lost the next impending major war. They've spent the past 25 years blowing trillions on purposefully unwinnable wars that serve to enrich American oligarchs. This has left the American military structurally weakened and mis-optimized to fight small groups of terrorists instead of fighting an enemy with comparable and perhaps superior ability.

We've also seen the decimation of the manufacturing base in America and with it the economic security that it provided the middle class and with it the power and skill set that comes from being able to design and build thing. Finally, the United States' recent choice to blow half their stockpile of numerous kinds of missiles all all at once while at the same time lacking the supply chain or even the manufacturing base to adequately restock their munitions as the nail in the coffin for the American empire.[2]

So what's going to happen in a world where America can't win a global conflict but is still protected from invasion by thousands of nuclear weapons? America is going to decline into a regional power that attacks its neighbours with impunity. You're already starting to see it and it won't be long until you see articles like this[1] about Alberta.

I don't want it to be this way, but it is.

[0] https://news.ycombinator.com/item?id=43487443

[1] https://www.thedailybeast.com/trump-hit-with-demand-for-answ...

[2] https://www.csis.org/analysis/last-rounds-status-key-munitio...

China is not an irrational actor. They know that the most effective way to take Taiwan is slowly, through soft power and political subterfuge.

There is no need or advantage to a full frontal assault.

The Europeans didn't think it was a bluff.

But more generally, when the foundation of your country's morality is "all men are created equal" you really have given up the space to object to others doing what you do.

If honour is a thing.

When both are true at the same time, one might reflect on why "because China" is given as the pat answer.