I don't think the North Koreans slowed their reasearch into Atomic wepons down for Carter and Clinton , diplomacy for them is a matter of what s mine is mine and what is yours is negotiable. Unless they could see the future when they started to build atomic bombs , President Bush's "axis of evil " comment couldn't have made any diffrence.
The time to act militarily is immediately , it takes time to refine Urainium or extract Plutonium , they have the fewest number of atomic devices right now as they will ever have. If we strike them with very heavy bombing they will never assemble another one .
No, we do not have enough troop strength availible to occupy North Korea and establish controll and order.
We do have enough air power to make truck travel on the road to the nuclear assembly plant absolutely impossible. That is all we really need to do , you cant carry much nuclear fuel in a knapsack.