Do both and within a year China will be a pre-industrial country of maybe 100-200 million. And all that without firing a single nuke or engaging in a land war.
Yeah, but they can do the same to us. They currently have naval superiority. Also, from what I have read, both China and NorKo are likely superior to us in cyberwarfare.
Also, if you want to put the tinfoil on, thousands of Chinese recently illegally crossed the Southern border. Those are the ones we know about. Combine that with the Wuhan lab and that if it were a test, a very successful test of the US reaction to a non-lethal proto-bioweapon. Make it lethal.
Or the third option, the Chinese could just finish buying up every piece of real estate in the US.