Unfortunately Kim is the smarter of the two.
What would you do about DPRK?
Kim Jong Un is an extremist, an attention whore. He won't ever change or be open for arguments. You can for example see extremist in action here in the thread no matter how wrong they are how inhuman their thinking is they will never change. You can only use them and try to get them to make even more ridiculous statements until the own people want him to go away. In that case it is necessary that you talk to him try to lift sanctions so more and more people of that country can get in touch with the rest of the world, remove the isolation. This will cause many people to have a change.
Examples exists a lot like the former communist eastern European countries, even with Cuba this started to work and will work if more and more sanctions removed and contacts established ...
If sanctions don't work it doesn't make sense to keep them for decade after decade. Better remove them and thus open the country.
Btw. No matter what the US will do they won't be able to avoid North Korea develop their nuclear weapons.