I wouldn't worry to much about the North Koreans having a viable nuke, along with the means to deliver it. The Chinese for one would never allow the N-Koreans a nuclear capability, any more than they would allow the Japanese, or the option to use the nuke. The Chinese are the big dog(Asian nuclear power) in that neck of the woods. They intend keep it that way.

What do you think of South Korea starting its own nuke program? It actually tried to during the seventies but abandoned the idea at the urging of the US. The US is an ally willing to come to the aid to the South but can the South rely on the US to use its own nuclear arsenal to deter a North Korean nuke attack on the South? Will the American public be willing to support nuking Pyongyang if Seoul goes up in a mushroom cloud? I don't think it is unreasonable to say that many Americans would not support a nuclear attack on anyone at all short of an American city being nuked. Therefore, I ask again, can South Koreans rely upon the US as a nuclear deterrent, or should the South (aside from concerns about nuclear proliferation) consider developing its own nuclear program to remove any doubts as to a nuclear response in Pyongyang?

South Korea wanted to develope its own nukes in the 70´s but due American pressure they abandoned that. They have also accepeted international agreements on nuclear weapons so it would be illegal to develope them- if they did so then they would be nothing better (in that matter) than those so-called rogue states, axis of evil or whatever one wants to call them. If the war is flamed in Korea peninsula it will be 100% sure that Americans are inolved and if I were North Korean I wouldn´t count on that I could match Americans in conventional warfare. So I would throw the hot stone on them and/or some nasty bio/chem stuff. So I think that South Koreans can rely on USA in this matter.