The insanity of North Korean government leaders seems to be growing with each long-range missile launch and nuclear weapons test. Recently, Kim Jong Un, the new "beloved leader" of the starving, poverty stricken Korean people, has made so bold as to declare the cease fire that ended the Korean War in 1953 to be null and void, as far as Kim is concerned. In other words, he considers North Korea at war with the US and anyone else who wants a piece of him.
There is growing sentiment in South Korea and elsewhere that South Korea should develop its own nuclear weapons program to counter North Korea's agresssion. That makes no more sense to us than trying to stop a gang war by equipping the fighting gangs with more and bigger guns.
For decades the US and the Soviet Union had a nuclear stalemate called MAD - Mutually Assured Destruction. Neither side wanted to start a nuclear war because both knew the other side had more than enough weaponry to destroy the enemy in response. It would be an act of insanity to launch a nuclear attack, and neither side was insane.
The same cannot be said for North Korea. We don't know if it's hereditary or just bad upbringing, but Kim Jong Un is as nuts, if not nuttier, than his dad and grandfather. If South Korea were to develop a nuclear arsenal, North Korea would see that as another threat and might possibly hit the launch button.
It is best to continue with strict sanctions, and hope China and Russia can talk some sense into this regime.