The real concern is that Iran would do what Pakistan did. Pakistan wanted nuclear weapons, like Iran, purely for defensive reasons - to defend itself against India. The problem was that once Pakistan acquired the weapons, it allowed the country to be more aggressive. So they stepped up their support for the Kashmiri terrorists, and it led very quickly to the Kargil crisis in 2000, which almost sparked a nuclear war between India and Pakistan.
Kenneth M. PollackI think if you could remove all of the baggage - all of the ideology, the history, whatever else - and look in purely geostrategic terms, I think it's hard to figure out why the US and Iran would necessarily be in conflict. In fact during the shah's era, before 1979 - recognizing that there were all kinds of other problems - the US and Iran worked together splendidly at the strategic level.
Kenneth M. PollackThe Europeans are starting to show that they're finally serious about the Iranian nuclear program, and they appear to be willing to use sticks against Iran. So I think it is imperative that the United States sit down with the Europeans and say, "Let's make this very clear to the Iranians. Either they can give up their nuclear program and their support for terrorism, in which case we'll given them all kinds of benefits. Otherwise, we'll join in comprehensive, multilateral sanctions that will cripple their very fragile economy."
Kenneth M. PollackMore likely, there were probably some real divisions within the Iranian government - some groups wanted to ally with al Qaeda against us, others didn't want to have anything to do with that. So I think that debate resulted in no decision being made for awhile. The problem was they left the al-Qaeda folks in Iran in the hands of their intelligence services and Revolutionary Guard, who didn't really keep an eye on them - and may not have kept an eye on them on purpose.
Kenneth M. PollackIran uses terrorism very instrumentally as an element of foreign policy; they are not just intent on just killing as many people as possible, like al Qaeda. There's no reason to believe that would change.
Kenneth M. Pollack