north korea realised its cannot maintain parity and equal military against south korea and america so asymetric response was with nukes ,
tactical and inter-kontinental.

tactical of small range woud crush south army ,and longrangeos ones will keep amerika away. norths army would survive in underground tunnes ready to take over ,and march on command.

this pace was accelerated especially after amerikan invasion of south iraq in 1991,where big conventional army was destroyed.
noth korean military planers were very smart.