Here's a qoute from an article i can't link to.
"This overarching problem is accentuated by the fact that everybody in the Middle East—our friends, foes, and folks in between—has correctly concluded that the administration has begun America’s disengagement from the region, on a scale unseen since the days of the British withdrawal from “East of Suez.” This has manifested itself in virtually every facet of our Middle East policy, from our failure to maintain any American military presence in Iraq and the consequent loss of diplomatic and economic influence in Baghdad; to Washington’s unwillingness to rally the American public to support our military efforts in Afghanistan and its repeated snubs of our strongest traditional Middle East ally, Israel; to our leading from behind on Libya and the total failure to lead from any direction on Syria; and last but not least, to our timidity in confronting the Iranian nuclear weapons program. As a result, the Middle East elites and the proverbial “Arab street” have concluded that the U.S. is a waning power, Israel’s future is one of a besieged state that someday may disappear from the regional chessboard, and Iran has an excellent chance of becoming a regional hegemon, to be feared and placated."
And I'd say it goes further back to the iraq and afghanistan invasions, post 9/11 the military commitments were only a fraction of what the u.s was politically capable at the time. So barring a leader like Sarah Palin, Iran is getting that nuke cause it knows u.s hasn't got the political will to stop them.
Best chance we have now is kicking the can down the road. If next administration bombs iran heavily or more. This will buy enough time for the next administration, where a leader like sarah palin might come into the picture. She could muster a credible invasion force, which if used as a threat, would make iran surrender to all demands. Granted probably only as long as the threat of invasion loomed.
However religious or irreligious the average Iranian is, & however much they like Americans, will not make any difference to their reaction to an invasion. They'd fight hard, very hard, & even the greatest American-lovers in the country would revile the USA.
Americans were greeted as liberators by many Iraqis in 2003. That is unlikely to happen in Iran. There is no single dictator, no individual & his family & cronies looting, raping & murdering for fun. Iran has an indigenous & fairly power structure, in which, despite its numerous evils, many individuals & groups have a stake. Most Iraqis belong to religious & ethnic groups (Shi'a, Kurds) which were excluded from the power structure, actively discriminated against, & violently repressed. Most Iranians are Shi'a, & either Farsi (Persian - 50%) or Azeri (half the rest), & those two groups run the country.
Iran would be harder than Iraq, much, much harder.
Iraq was invaded and occupied by a very hobbled u.s military and a very incompetent state department, and it was pretty easy. So as long as the iran invasion is of a reasonable size and the state department is semi-competent, I don't think it will be difficult. Iranians standing their ground will just mean dead iranians in the face of superior u.s firepower, skill and morale. And I repeat the u.s has learned alot from the iraq invasion and occupation experience which will make them even more effective. And let's not forget what the iraq war has taught iranians, mainly that resisting a u.s invasion and occupation will only make iranians suffer more and is doomed to failure. And generally speaking a u.s occupation isn't that bad. And iranians will realise this as they have a significantly higher literacy rate than Iraqui's, interestingly at almost 99% for 15-24 year olds. (which tells us how sophisticated the current generation is)
The fact the regime has alot of support by it's people makes things easier not harder. The regime will cooperate with a u.s invasion force because it's leadership wants to survive. In iraq the u.s presumably viewed the existing leadership as too despised to make a good partner, this made things more difficult. In an Iran invasion, Khomeni doesn't have to hang and the existing regime doesn't need to be destroyed. The main aim would be to make the existing regime not develop nukes and not to attack the u.s, a goal that wouldn't be difficult if there's an army parked in the country.
Also ironically, the iranian peoples desire to be a hegemonic power in their region would never be closer to being granted, once they have the ear of the u.s and their cooperation naturally evolved into an alliance. I'd prefer iran as an ally over saudia arabia. (or as a mid east 'leader') Also if islam is going to be reformed a good starting point would be the sunni-shiite conflict. If they can't stop killing each other, then there's no chance in trying to stop them killing us. (israel included)
