I agree with everything Andrew Sullivan says in this series of posts.

An excerpt:

But now we have the reality of completely weak states, or parasitic states, or failed states or neo-states (like al Qaeda) getting nukes by buying them, or stealing them or smuggling the component parts. They can also find ways to detonate them anonymously so that the civilized world is incapable of rational response or even rational deterrence.

And another:

Our current U.N. (which includes rogues states and makes no distinction between them and others) naturally doesn't recognize such a double-standard. Moreover our civilized partners simply don't believe that the threat is that grave. Even after 9/11, even many Americans don't believe the threat is that serious. This is therefore the key context of our current impasse.

Go read them all and let me know what you think.