In my view, it's all fear-mongering. And, as I said, I don't believe a word any of these hawks tell me. It's just sad that this nonsense has polluted our side of the aisle. The Bush Doctrine has got to go, and it's absolutely shameful that Democrats are reinforcing it. (This, more than anything else, is why I'm going to have real trouble showing up on November 4th.) But, as Bill Maher once said, Americans would eat paint if you spent enough money on advertising. Conservatives want live babies so they can raise them to be dead soldiers. - George Carlin
Ignoring that - the bravado about punishing North Korea for selling Nukes is simply that - unless one is willing to risk the quite likely possibility that if they have nukes to sell, they have made a certain amount of effort to safe keep nukes for a second strike.
As Sibel Edmonds as point out - forget about N. Korea when it comes to selling nuclear secrets. Pay attention to a country far closer to home - the United States.
aspiring to genteel poverty