North Korea and its bottle rockets are a sideshow. Let me put this to you in culturally resonant terms: reclaiming tianxia is China's Manifest Destiny. You are standing in the way of that Destiny, and that doesn't end well for you. If you don't find a way to extricate yourselves, one of the following two things happens:
If you find neither of these options appealing, it would behoove you to find a way to exit China's near-abroad expeditiously.
- China delivers an ultimatum which you obey, resulting in a humiliating withdrawal.
- China delivers an ultimatum which you defy, resulting in your skulls getting stomped into paste.
Whatever you say. If China wants Manifest Destiny, let them try.
I don't think the Viets would agree with that terminology, unification more like. The North and the South of the Peninsula will unify in the future and when they do the US can stop occupying it.
Ask the Vietnamese who fled. If North and South wants to be unified, then tell North to try again and invade in the name of unification.