The problem is that NK has thousands of traditional artillery pieces stationed along the DMZ that are capable of hitting Seoul and other large population center

The problem is that NK has thousands of traditional artillery pieces stationed along the DMZ that are capable of hitting Seoul and other large population centers [0]. They also have short range ballistic missiles [1] which can reach much of South Korea. So negotiating with them has been dicey. Especially since they have figured out that "If we do this thing the west doesn't like, we can go to the negotiating table and get them to send us food." I do want to point out that the war never ended in 1953 - there was just an armistice signed, so technically North and South Korea are still belligerents. So far as the DPRK leadership acting rationally - by their standards, they are. From talking with people who have visited there - the North Koreans have a world view that is substantially different from everyone else on the planet. [0] https://en.wikipedia.org/wiki/M-1978_Koksan https://en.wikipedia.org/wiki/M-1978_Koksan [1] https://en.wikipedia.org/wiki/KN-25 https://en.wikipedia.org/wiki/KN-25