A sovereign nation stays sovereign not because it can defend itself, or because of the treaties it has in place, but rather because of the way the people there delineate the mental boundary between “us” and “them.” The government of a country can sign away every legal element of there being an independent country, and yet still not destroy the sovereignty of the nation of people that exists there. Before and after legal annexation, it’s still just as hard to absorb that “country” into your own, because the legality of doing so was never the blocker.

Empires want productive colonies. They don’t go around conquering land just to kick everyone who lives there off and move their own citizens there. They want to capture the GDP of the existing nation-of-people, and have that GDP become part of their aggregate GDP, advancing their ends. So empires are unwilling to do anything to conquer a nation-of-people that destroys their GDP in the process. They don’t want to start with a first-world neighbour and end up with a third-world satellite.

And nations-of-people, who actively resist thinking of themselves as part of a given empire, when the order comes down to work toward that empire’s ends—they’ll just not work. They know they might be sent to “labor camps” in said empire, to get a little productivity out of them—but they also know that this is still a destruction of economic value from the empire’s perspective, since they were doing labor before which had far more economic value than the labor the empire can coerce out of them in a labor camp. So they know that, by and large, the empire won’t bother to do this. They might try doing it a few times, as a terrorist tactic to scare the nation-of-people into compliance... but they don’t want to actually do enough damage to the GDP of the annexed state to matter.

Or, to put that another way: a nation-of-people under annexation is like a city made of glass, under siege (where “made of glass” refers here to both the city and its people.) Sure, anyone could just go in and break all the glass, if they wanted the city wiped off the map. But—at least in the modern geopolitical landscape—there’s no reason to want to. Everyone wants to capture the city. And that’s basically impossible by military means, because the military tools empires have available to them are designed to shatter glass. They’ll end up with a big heap of nothing, rather than a city. The only way to make the city yours is to just convince its citizens that they want to work for you.

And, if an empire is in a negotiation at that level, they’re essentially back to negotiating with a peer sovereign nation. They can’t truly dictate law or custom, because the citizens (as-yet unintegrated, still thinking of the empire as “them” rather than “us”) won’t work under those conditions, and there’s no way to force them to do so without killing the golden goose.

——

China is in a holding pattern with Hong Kong. They think they can, through secular drift, get future generations to think of themselves as just “Chinese”—to think of the Chinese empire as “us” rather than “them.” At that point, the game is won, and China can enforce whatever laws and customs they like on Hong Kong.

But until that point—and, perhaps, that point may never come, if the citizens of Hong Kong continue to raise their children to see themselves as “citizens of Hong Kong” first-and-foremost—China can only put in place such laws and practices as the citizens of Hong Kong will tolerate.