Because Yemen is offically an ally, and it wasn't the smoking gun that the Bush White House was hoping for.
Now missiles are not particularly useful without a nasty payload, and high explosive isn't that nasty. Biological weapons are hard to disperse. Chemical weapons have a similiar problem, and do nothing to undermine enemy infrastructures, having use in being a terror weapon or against enemy forces. And I'll give my consent to any government that does not deny a man a living wage-Billy Bragg
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. WHEEEEEEEEEEEEEEEEEEEEE!
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. We are for Justice and Mercy, and Truth and Peace, and true Freedom. Edward Burroughs 1659