'Indeed, I would argue that because Sunni Arabs from Saudi Arabia, the United Arab Emirates, Lebanon, and Egypt perpetrated the attacks of September 11, 2001, and because Sunni hostility to American and Israeli interests remains a conspicuous problem, the United States should theoretically welcome a strengthened Shiite role in the Middle East, were Iran to go through an even partial political transformation. And demographic, cultural, and other indicators all point to a positive ideological and philosophical shift in Iran in the medium to long term. Given this prognosis, and the high cost and poor chances for success of any military effort to eliminate Iranâ??s nuclear program, I believe that containment of a nuclear Iran is the most sensible policy for the United States.The success of containment will depend on a host of regional factors. But its sine qua non will be the ability of the United States to underline any policy toward a nuclear-armed Iran with the credible threat of military action. As Kissinger told me, â??I want America to sustain whatever measures it takes about Iran.â? As he writes in Nuclear Weapons and Foreign Policy, â??Deterrence â?¦ is achieved when one sideâ??s readiness to run risks in relation to the other is high; it is least effective when the willingness to run risks is low, however powerful the military capability.â? - Robert Kaplan
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I think Kaplan has it right in the first graf, but I'm not so sure about the second (even if he does invoke the Godfather of Realism himself). The fundamental problem with any containment analogy and Iran is the question of what we're supposed to contain. With the Soviet Union it was clear enough: we were checking Russia's expansion and blocking the spread of communist governments worldwide.
It's unlikely that Iran is going to physically invade any of its neighbors - with or without a nuclear weapon. Iran can achieve some measure of regional power through the use of its proxies, but that's something it's been doing for years now. It's not clear to me what containment has to do with that (or how, frankly, it could stop it). So what are we containing?