I don't believe the North Korean ruler is insane. And if it was just a North Korea nuclear problem, I think we could deter and contain North Korea. We really have an Iran problem.
Seriously, North Korea has not rolled the dice to attack South Korea since the armistice suspended the Korean War in the middle of the last century. They didn't do it when they had a decent shot at winning such a war and a Soviet ally to deter our nuclear forces. Would they really try it now?
Even with nukes that deter our nuclear response?
Would North Korea really launch at one of our cities?
When we might shoot it (or them) down? And when we'd nuke North Korea in return even if we shot down every North Korean missile? (Not their cities. We aren't mass murderers of innocents. But we would have to nuke a number of North Korean military and nuclear assets if we didn't want to see our nuclear deterrent reputation dissolve in the mistaken notion that "no harm, no foul" rules apply.)
Victor Hanson says that we can't attack North Korea to destroy all their nukes and we can't live with a nuclear-armed North Korea.
I think that we can't live with a nuclear-armed North Korea as long as it has a nutball-run Iran with the desire to get nuclear weapons and the cash to buy them from North Korea.
Seriously, all the promises Iran has made to limit--for an increasingly short time frame that will end before you know it--their domestic nuclear programs don't cover buying nukes from someone. From someone like North Korea that is desperate for money.
Even assuming success with Hanson's response of a long expensive struggle to build the capacity to defeat North Korean nuclear missiles that avoids the shortcomings of attacking North Korea yet refuses to live with the threat, the problem of Iran as a nuclear customer remains.
North Korea may be rational enough to deter. But is Iran with their religious zealotry that may embrace nuclear flames to purge the world and bring their time of glory out a risk we want to take?
Supporting a revolt of Iran's long-suffering people to get rid of the mullah-run regime would make the North Korea problem more solvable.
Indeed, getting rid of Iran's mullah regime cuts the Gordian Knot for a lot of our problems.
UPDATE: Iran strongly hints that it would shoot missiles at our troops in the Middle East if we impose sanctions on Iran. American troops at bases in Arab countries.