Does anyone here have a guess as to the fat kid's motivations, why he's doing this?
What do you suppose is his ultimate goal?
He wants to deter regime change. It's the first thing out of NKorea negotiator's mouths when they were negotiating with Bush. They believe that the US will do to them what we did to Sadam and Qadafi. He believes that having a nuclear capacity is his only protection.
Couple of facts:
Clinton negotiated a deal in 94 that restricted NK from pursuing fissile material. They cheated, looking for uranium rather than plutonium.
When Dubya took over he knew they were cheated and refused to negotiate... until 2006 when they detonated their first baby bomb..
Then Dubya ran back to the negotiating table.
Interestingly South Koreans don't really pay attention to Kim's blathering threats. They deal with it every day.
So (you didn't ask but I'm volunteering) what I'd do:
->
Don't over-react. Don't fall into a bluster/bravado match with a 33 year old. "Don't wrestle in the mud with a pig, you'll both get dirty and the pig will love it."
-> Tell them, without bluster or bravado, that
if they attack US interests they will be attacked. Define "US interests very clearly to include actions (not threats) against our allies, and include missile tests that overfly allies if you want, although that is a bit tricky given altitude telemetry etc.
-> Tell them, without an attack on US interests as defined,
we will not pursue preemptive regime change. (We will however do all the spying and cyberattacks that we want).
-> Work on
intensifying sanctions when NK does stuff like they did today. China is the key here, and we need their help.
-> For God's sake don't pick this week to
tell South Korea that you might back out of a trade deal with them. Timing is everything, and maybe wait a month or two, maybe?