[peder]

> The less snarky answer is that our current system does not have a functioning global government

What an odd thing to say. Even when there were monolithic governments ruling over certain sphere of influence like the USSR over Eastern Europe, you still had countries break ranks like Yugoslavia and Romania. A single unified government does not mean that individual actors do not know and use their own leverage to advance their own interests.

North Korea is independent for a variety of reasons, and it's not clear that a pro-US North Korea is an all-around win with no downsides for the US. I think both the US and China like having buffer states to avoid flashpoints for war.