It is obvious, isn't it? China does not want any close American allies sharing a land border with it. Which is why China tolerates Kim Jong-un, and is obviously investing heavily in countries like Pakistan to contain India's ambitions (a country with which China has less-than-friendly relations). Russia serves a similar purpose.

Anyway, you've interpreted my article wrongly. In fact, I'm drafting a follow-up article in which I argue that it would serve everyone's interests if the USA and China made peace with each other.