NK is in the process of disarming itself simply by launching it's own missiles. At the rate it is going it will soon be defenselessness.  That's is the trouble with being a hermit state. there is no industrial complex,  no research, no education, no manufacturing not in  the control of the myopic government.  Each missile is a one -off.  Each nuclear bomb is a stand alone. They have no way to manufacture  other things like cars,  metallurgy, electronics, and plastics,  which builds  the foundation for making weapons.  Even China knows the value of the private sector doing advanced research for the government.