As much as I hate Trump, none of this is his fault. If we have to address this at the root, it's China, the pink elephant in the room. China, our biggest trading partner and also an authoritarian government (US is probably kicking itself allowing such a horrible actor to be so powerful), is propping up this vassel state and prevent any progress made in the peninsula. If China wasn't propping them up, North Korean government would have already fell long time ago.
So what happens now? Do we just let China keep protecting its puppet until the puppet has shipped a nuclear bomb to a port in Los Angeles? I hope not. I hope the world takes action before then.