Picture courtesy of BBC.
An attack by the Israeli's, or by US forces, will likely result in the death of hundreds of thousands if not millions of Iranians. And while I recognize the significance of Iran's nuclear progress coupled with its president's horrific statements, one cannot view Iranian politics or foreign policy from a superficial perspective. The president, Ahmadinejad, has no military authority nor any real political power. One needs only to view former president Khatami's failure to actualize reform policies as the barometer of Iranian presidential weakness. Ironically, the Iranian president is more a weapon of mass destruction to his own people, than to foreign nations. The question is, whether the powers underlying the negotiations and nuclear planning are guided by "ideological imperative and nationalistic determination" such that the program can never be negotiated away. To begin with, it is clear that Iran is treated and negotiated with differently than other states, authoritarian or not. The significantly different treatment between the "haves" and "have-nots" is essential in characterizing Iran's fear. Generally, a number of variables have been looked at to explain why a country would go nuclear. Two of the most prominent which have emerged in the Iran "nuclear discussion" are prestige and territory (or geo-political stability).
Prestige: every country which possessed nuclear weapons at the time the UN Charter was drafted is now a permanent member on the Security Council. Many scholars have postulated that "hegemony" requires nuclear weapons. Thus, for a country to reach the status of a regional hegemon, it must possess nukes. I don't think this argument is that persuasive. A number of countries, including Germany and Japan, have successfully become regional hegemons by becoming economic powerhouses. However, what every "strong" country possesses is a nuclear infrastructure. It goes without saying that every major global and regional power is capable of creating and running its own nuclear cycle. It is enough to say, therefore, that if Iran wishes to be viewed as a global, or regional, player it must be capable of exploring nuclear technology. However, to postulate that prestige motivates Iran's design to acquire nuclear weapons is both insincere and dangerous. While the Iranian people are highly prideful, particularly to their technological and scientific progress, the vast majority of Iranians have clearly indicated that they desire nuclear technology and not its military uses. There is pride in possessing nuclear technology because it reflects the advanced character of science in Iran. There is a clear distinction, however, amongst Iranians between the character of science as reflected by knowledge and possession of nuclear technology, and militarization of nuclear devices. Subsequently, at least on the grassroots level, it is inappropriate to think that "prestige" is motivating the Iranians to "go nuclear" in the military sense.
Territory: The second and more important reason why countries go nuclear, is because of territorial threats. The more a country views its territory to be threatened, the more likely it is to develop nukes. The US, Russia, France, Britain, and China in reaction to WWII and the Cold War. India in reaction to China. Pakistan in reaction to India. Israel in reaction to the Arab states. South Africa in reaction to Angola and international pressures against apartheid. North Korea in reaction to South Korea and growing international pressures. Even alleged programs are reactionary. Iraq, under Saddam, in reaction to Iran. Argentina and Brazil in reaction to each other. Egypt in reaction to Israel. And so on.
With the removal of both the governments in Afghanistan and Iraq, Iran faces no territorial threat. In fact, it faces two governments which are highly favorable, if not inspired, by its existence. The question is whether the looming American presence is enough to constitute a territorial threat. I don't think it is and I don't think the Iranians think it is either. Generally, territorial threats are tangible. For one, the Iranians know that the Israelis do not possess the capacity or the desire to overthrow the Iranian regime. Secondly, the US administration is so entrenched in its own war in Iraq and Afghanistan, that it simply lacks the manpower or popular sentiments to engage in a full war with Iran.
The Calculus: There is one fundamental issue to keep in mind. The pursuit of nuclear weapons is a highly costly venture, both in monetary and political terms. Post-NPT nuclear states spend billions of dollars, are politically isolated, and are closed off from global markets for decades. In the vast majority of cases where states have sought to acquire nuclear weapons, or possessed nukes by virtue of dissolution, the pressure imposed by the international community has generally succeeded in stopping completion of their objectives or continued possession of weapons. Subsequently, every state that pursues nuclear weapons must generally determine through some political calculus that the deterrent capability far outweighs its political, economic, and structural consequence. That being said, an Iran which is attacked is far more likely to weaponize its nuclear program then an Iran which is negotiated with. Now put other variables in perspective. Iran currently faces an economic crisis wherein its unemployment rates probably near 25%. Its leaders understand the political consequences of economic problems. In fact, every presidential candidate made the economy the focal point of their campaign. In all real terms, the vast majority of the population was sympathetic to a candidate which promised to make Iran an "Islamic Japan," clearly drawing reference to Japan's economic power. An attack against Iran does nothing more than draw attention away from its economic problems and burgeoning democratic movement. In other words, an attack on Iran does more to further Iran's nuclear ambitions, than lessen it.