Many also scoff at the notion that a responsible Iranian leader would risk using or transferring nuclear weapons or technology. We are told that Ahmadinejad (who most acknowledge is crazy enough to use such a weapon) won’t make the final decision. But the regime is remarkably opaque, and shifting power centers ensure that even capable intelligence agencies have low levels of certainty about decision-making in Iran’s nuclear program. ~Danielle Pletka 
As one of the scoffers, I would add something else. That parenthetical statement about Ahmadinejad’s insanity does a lot of the work in a piece aimed at instilling fear in its audience. We heard quite often how “mad” Hussein was in the years prior to the invasion. As we now know for certain, he was so utterly preoccupied with self-preservation and projecting an image of strength that he went out of his way to appear more dangerous than he was to make enemies think twice about attacking him. As the rigged election and crackdown this summer have shown, Ahmadinejad is concerned above all with keeping himself and his allies in power.
Ahmadinejad has shown himself to be the most cynical, self-serving political operator. This is hardly the kind of person who would hand over a nuke to a third party even if he were in a position to do this, much less order a nuclear attack when he and his allies would stand to lose everything in the retaliation that would follow. It is improbable that a constitutionally weak president, who does not have authority over the security apparatus or foreign policy, would be in a position to make a decision as crucial as the sale or use of nuclear weapons, but even if he were making that decision we have little reason to think that he would willingly hand over such a powerful weapon and even less reason to think that he would order an attack with such a weapon. So Iran policy hawks have to trot out the “crazy dictator” line to get around the problem that all of their frightening scenarios are far-fetched and unreasonable.
The Iranian government is relatively opaque, but like any modern regime it is made up of a large number of people and institutions that have their own interests in self-preservation. Even if Iran one day had a nuclear weapon (which it doesn’t have right now!), and even if Ahmadinejad were in a position to give away, sell or use such a weapon, you have to assume that there would be a near-unanimous consensus inside the upper echelons of the Iranian government that this is a desirable thing to do. More to the point, you have to assume that there would be no violent attempt from within the regime to stop such action. As Pletka herself acknowledges, the regime’s structure is opaque, so we cannot assume that there is anything like a consensus inside their government about what Iran should do with any nuclear weapons that it might acquire. This is understandable, since it does not yet possess these weapons and won’t have them for many years. Even if Ahmadinejad were “crazy,” as Pletka assumes without any real evidence*, that doesn’t mean that all of the people in the military, the IRGC and the clerical establishment are suicidal.
Pakistan is a useful counter-example that disproves the hawks’ fantasies. Pakistan is a state that has used terrorist and militia proxies against it enemies for decades. Pakistan is at a significant disadvantage against India in conventional warfare, which is why it has relied on terrorism and proxy warfare since the loss of Bangladesh. It has actually possessed a sizeable nuclear arsenal for over a decade. If ever there were a candidate for a nuclear-armed state giving nukes to terrorists to achieve its political goals, Pakistan is it, and Pakistan has not done this and is not likely to do this. While there was a dangerous moment during the Kargil war when the conflict almost escalated disastrously and there were extremely heightened tensions earlier this decade, the Pakistani military had complete control over its arsenal and it was not about to hand off one of its weapons to Lashkar-e-Taiba or one of its other proxies. Not only would this deprive Pakistan of control over how and when the weapon would be used, but it would still make Pakistan responsible for the weapon’s use, the weapon would be traced back to Pakistan, and this would lead to serious Indian retaliation against Pakistan. When nuclear weapons are involved, deterrence seems to prevail every time.
As Greg Scoblete  makes clear, the “the real fear is not that the lives of Americans are in any concrete danger when Iran goes nuclear but that the power balance in the Middle East might tilt in Iran’s favor.” The thing to bear in mind is that the power balance has been tilting in Iran’s favor for the last six years thanks to the rise of pro-Iranian Shi’ite parties as the leading parties in Iraq’s government. Iran is a leading regional power, and it is going to exercise more influence over time. It is going to seek and eventually acquire nuclear weapons to counter-balance the numerous other nuclear powers in its neighborhood, several of which are openly hostile.**
We already have the means to contain Iran. Except when we have toppled their worst rivals and empower their proxies, we were already containing Iran. What so many Westerners seem not to understand is that if Iran pursues a nuclear weapon, it is doing so to acquire a deterrent to limit the aggressiveness of hostile states. In other words, the question the Iranian government is asking is how it can “contain” and deter the U.S. and our allies.
* Treating Ahmadinejad as a “crazy” person is a mistake, because it means that we believe that only a madman would hold the beliefs that he does. We don’t quite know what to do with an urban engineer apparently in complete control of his faculties who nonetheless holds some of the most obnoxious political views. Indeed, when most people label this or that foreign leader as “crazy,” I’m guessing they don’t mean that he is out of his mind. They mean that they don’t like him. As a descriptor of political leaders, crazy is fast becoming as meaningless as fascist already is.
** The amazing thing about the Iran debate is that many of us in the West talk about the possibility of bombing Iran the way other people talk about the weather. It might rain later today. Israel might launch military strikes on Iran. I recall an article  in The Wall Street Journal over two months ago outlining the technical difficulties of an Israeli air strike, the armaments that would be used and the targets that would be attacked. There is a remarkable non-chalance about aggressive war against Iran that would send the very same people into apoplectic fits of rage if state-run media in one of these authoritarian states blithely discussed attacking installations in our country. Hawks would take such talk from the Iranian media as proof of hostile intent and a justification for “pre-emptive” action.