For 60 years South Korea has been "under the thumb" of the USA - and as a result is a vibrant, prosperous democracy with a HUGE economy and bright energetic very well-educated people.
For 60 years, North Korea has been under the thumb of China (and to some degree the USSR and Russia).
And as a result it is a horrifically poor nation starved of all things including human rights - and it's a huge threat to the region. A NUCLEAR threat.
This tells us everything we need to know about the USA and China.
China is evil.
The USA is great and good.
We cannot fix the situation in North Korea without coming down very hard on China.