The nuke issue is enough to go in.
Letting them continuously test missiles is just another reason to go in.
And in all honesty, I don't know if he is the only thing standing between NK joining normalcy. I'm not sure to what extent NK believes they are an international pariah. It's not like they are even very cognizant of the outside world. Everything that I've read is that they revere them as demi-gods. Generations of brainwashing, with fear and reprisals a normal way of life...
They very well may have lost their desire to fight the system.
~Jeordam
Saving the Princess, Humanity, or the World-Entire since 1985