Montanero, you got that right. Loads of countries have been wanting to "join the club" and have done everything they can to do so for the decades you mentioned - scary business.

It's a moot point at this stage. With the latest nuke test on Sep 2, 2017 N. Korea has pushed its bombs up to 100 Kiloton (give or take). This is a very powerful weapon. Can be used against entire cities, and would do tremendous damage. I doubt that they have the ability to put this bomb on a rocket yet. But I really don't think that the world will let this arms development continue.

Unless China has an unlikely change of heart regarding cutting off oil, food & other trade until NK halts its atomic weapon / missile programs, the world will have to live with NK as a nuclear power.

Alternatively, military options might succeed in the long run, but not without, at the least, the destruction of Seoul SK and 20-30million casualties and U S participation in another "Police Action" ( aka: War) on the Korean Peninsula. Baaad Idea! Military decapitation/ counter force ops might even end up in a general war.

Soooooo...... ( I cannot believe I'm about to say this), the best prep may be to quietly tell China that failing NK freezing said programs, we are going to GIVE SK and Japan their own atomic weapons, to insure a type of MAD ( mutually assuered destruction), hot peace. The conversation would include a hard date on which we would commence our atomic gift.

This would be a quiet announcement, initially privately delivered, perhaps a secret Tillerson trip to China, a la Kissinger. It would not be a Twitter tirade or a beilicose public threat.

Even if that threat doesn't work at halting NK, MAD has worked for almost 70 years. China and Korea fear Japan, with good historical reasons. China might even fear the possibility of a nuclear armed Japan/SK, enough to take some real actions to control NK. If not, MAD should still work. Anything is better than the U S getting into another land war in Asia

Sometimes smart prepping includes an asymmetrical collective national defense.

It won't be easy to convince Japan to accept becoming a nuclear power. They're pretty anti-nuke and committed to pacifism. Of course and existential threat from DPRK might nudge them a bit.

Japan is much more likely to be convinced to house anti-ballistic missile systems. They have decent relationships with both the US and Isreal, who have ABM technology, and I can't see much conflict with pacifistic philosophy.

Iron Dome seems to be a pretty effective system. Something like that may be useful in Japan. The good thing from their perspective is that their country isn't that large (ie not a lot of territory to protect). On the other hand it's a short flight by missile from DPRK.

Israel only uses Iron Dome for close in atmospheric air defense. They have the arrow 3 missile for ABM defense . A hypersonic, hypermanuvable, interceptor that hits incoming targets in space.

Asian news sources are already speculating about Japan buying a couple of the Arrow 3 systems.

http://www.atimes.com/article/japan-need-israeli-arrow-3-interceptor-missile/

Cool stuff!

"Asian news sources are already speculating about Japan buying a couple of the Arrow 3 systems."

A very good idea.
They need to buy more than just a "couple". :-)

Sounds like our missile defense shield is only 50/50, at best. http://www.defenseone.com/ideas/2017/09/no-we-cannot-shoot-down-north-koreas-missiles/141070/