National identity don't really matter. In past, entire south american continent was changed to Western outlook and Christianity. The playbook is very simply for this: change school curriculum, medium of instruction, replace religious leaders, control media outlets, full on propoganda, remove dissendent and promote people who complies. If you don't care about human lives, you can change national identity within 3-4 generations.
> After first contacts with Europeans and Africans, some believe that the death of 90–95% of the native population of the New World was caused by Old World diseases. It is suspected that smallpox was the chief culprit and responsible for killing nearly all of the native inhabitants of the Americas.
I had read an account of someone from a tribe conquered by Rome which outlined exactly this. He complained about how his kids were educated in the Roman way, refused to speak the old language, identified with the new place, etc.
I saw a lot of common bits to how immigrant integration as I experienced in the US (granted, immigration usually implies consent where being conquered doesn't): the cultural divide between children and parents, new national identities, etc.
If you harass everyone all the time, you’ll have the entire population taking up arms. Russia doesn’t have enough soldiers or drones to even attempt to prosecute that type of war.
Maybe China and India can win such wars with their huge populations that would allow them to completely alter the demographics of a country.