I wonder in such a case if more populous countries like India or China could in theory send over 100 million+ people to our country over the course of a decade, and then once those people are citizens, legally vote for the US to be annexed by China, etc..
You could conquer a country without a single shot fired.
Putting aside the blatant unconstitutionality of the question, how often does "should the US be legally annexed by China" come up on the ballot?
Yeah, sure, if Chinese people were ants in a hivemind that strategy might work.