"What will happen with Iran?" seems to be one of the consuming questions right now for those whose political interests stretch beyond the sordid lives of the inhabitants of Capitol Hill. Iran has made it's intention of becoming a nuclear power pretty clear. It's regime has shown a propensity for fighting proxy wars throughout the region (funding Shia militias in Iraq, and supporting Hamas and Hezbollah against Israel) and routinely refers to the US as the "great Satan". It's not the sort of place that you want sitting around with the ability to turn a mid-size city in to a glassy crater, and yet they've been careful to scatter their nuclear facilities throughout the country, with the most important ones built underground with enough steel-reinforced concrete above them that nothing short of a tactical nuke would succeed in blasting through.
There seem to be two basic lines of thought in regards to the question, and I haven't yet made up my mind as to which appeals more to me.
We Dare Not Let It Happen
This line of thinking essentially goes: "The leaders of Iran are religious fanatics who believe the end of the world is not far off and military victory is guaranteed them against the 'great Satan'. Thus, the chances that they would use an atomic bomb against us or our allies (either directly or through a proxy terrorist organization) are very high. We must draw a line in the sand and if Iran does not drop its nuclear ambitions then any military means necessary to make them do so must be used in order to prevent them from going nuclear. Even taking a less alarmist scenario, if they didn't attack us immediately, a nuclear Iran would have enough of a threat hanging over the region to operate even more freely as regards to funding attacks against Israel, funding militias in Iraq, etc."
According to this line of thinking, Iran getting it's first nukes puts us very, very close to Tel Aviv disappearing into a mushroom cloud, or some terrorist organization smuggling an a-bomb into the US. The solution, proponents seem to feel, is to put a very clear line in the sand out there, and if Iran tries to cross it, either stage a serious bombing/missile campaign against their nuclear infrastructure or make a series of lightning raids against Iranian nuclear installations using ground forces. Perhaps some of this comes from the lesson which some of drawn from the Iraq war, which is essentially that while pacifying an unwilling Middle Eastern population is a nightmare, there's not much of any country in the region which is capable of withstanding a couple US armored columns. Why not, the thinking goes, invade, destroy the nuclear facilities, and then simply leave, letting the existing Iranian government sort out the pieces afterwards.
There are two main questions opened up by this line of thinking.
The first is strictly practical: Do we really have the military resources to successfully destroy Iran's nuclear infrastructure, and is it vaguely realistic to imagine we could roll in, destroy that infrastructure, and get out again without causing a wider regional war?
The other question is: From both a moral and political perspective, can getting close to attaining the technology that would allow the building of a weapon which could in turn be used against us be considered "an attack" which justifies a military response? War is never a desired outcome, and there would doubtless be many innocent people killed if the US attempted to wipe out Iran's nuclear program. On the other hand, if Iran is allowed to "go nuclear" then it will then be holding the nuclear threat over civilian populations, both of local powers (primarily Israel) and possibly against the US as well. And in turn, the only way other nuclear powers such as the US would have of deterring Iran from using its newfound nuclear weapons would be by holding out the threat of a nuclear counterstrike, thus overshadowing all Iranian civilians with the danger of nuclear war. Ironically, it is possible that the only way to prevent a nuclear war with Iran with any certainty is to fight a conventional war with them first.
At Most a Regional Threat
The other line of thinking puts much less pressure on us right now. The question is, what does it open us up for in the future: "Say Iran goes nuclear within the next five years, which is quite possible. Even so, it's a regional threat on the other side of the world. Iran's air force is negligible. They certainly don't have stealth bombers. And rogue military powers (witness North Korea's recent escapades) simply don't have very good missile technology. So, short of smuggling something in to a port by ship, there's simply no way that Iran could stage a nuclear attack on the US or even Europe any time soon. Even Israel would be comparatively safe, since they have perhaps the strongest air force in the region, already have a reliable nuclear arsenal for deterrence, and the sort of missile technology Iran currently has might well not be better than 50% reliable at successfully hitting a major Israeli city. Thus, the US can afford to sit back and wait to see what develops."
While sitting back and waiting to see what a nuclear Iran would do is certainly an alarming concept, it does strike me as moderately unlikely that a) Iran would develop all that good a nuclear weapon, b) they would develop any time in the near future missiles reliable enough to deliver a warhead with any reliability, must less at any distance, and c) that they could successfully smuggle a warhead into the US by any other means.
All of these are certainly possible, no one should kid themselves that they aren't, but they're not very likely. So weighed against the near certainty of having to go to war with Iran if we are committed to military action rather than allowing them to go nuclear, there's a certain attractiveness to waiting and seeing. It's possible a nuclear Iran would never use its weapons, and if it did, the chances are at least decent that it would do so by attacking another country in the region (probably Israel) and that the bomb would either fail to go off or miss. (If that happened, one assumes there would be pretty wide consensus that it was now definitely time to invade Iran, with even other Islamic countries willing to either join in or look the other way.)
Still, the great uncertainly in this approach is that it stakes a very great deal on the assumption that Iran would be either too wise or too incompetent to hurt us. Given that these are opposite extremes, there's always the danger they would be wise enough not to e incompetent, but not wise enough to avoid a war. And then things could be very, very bad.