The question is, how dire a threat do you think this is? The Israelis, and some of their American right-wing allies, believe it is mortal. I don't. I think it is a consequence of Iranian pride and a rational desire for deterrence. As long as the Israelis and Pakistanis have the bomb, the Iranians will want one. After all, no sane mullah--and they have proven themselves to be quite sane, if often noxious, when it comes to foreign policy--could have watched the events of the last decade and not drawn the conclusion that having a bomb enhances Iran's national security. The other two members of the "Axis of Evil" offer a dramatic narrative: North Korea developed a bomb and hasn't been attacked; Saddam Hussein didn't, and he is gone.
Crowley also reacts.