The US isn't going to invade China; I mean, it fought North Korea to a draw and could stomach Vietnam, and you think it's going to make a credible threat to invade China over internal policy?
And, if it did make such a threat and China believed it, that would just drive things into high gear. When someone's already doing a plan that is basically forcibly assimilate or exterminate, a timeline just pushes it to expedite the latter.