Iran is gunning for Israel.
I must disagree with that statement. Iran wants to be left alone. Shortly after the US invaded Iraq, the Iranians sent the "Grand Bargain" fax to the US through the Swiss Embassy in which they offered all sorts of concessions (including recognizing Israel) in exchange for being left alone.
Bush/Cheney thought they were too cool, so they didn't even respond. As a result of their non-response, the Iranian moderates who were in power at the time were purged (some literally), and this led to the rise of the fundamentalists and Ahmajinedad's election.
I learned of this in an under-graduate polysci course, but a very good recap of the situation can be found here: http://www.pbs.org/wgbh/pages/frontline/showdown/themes/grandbargain.html
For more information on how Iran has repeatedly tried to work with this US, only to be rebuffed: http://www.pbs.org/wgbh/pages/frontline/showdown/
Think about that. But for Bush/Cheney, we would likely have normal relations with Iran and the moderates would have increased in power and implemented even more changes.
Most Iranians, including American Iranians who go home every year to visit, will tell you that they have long expected that the US would manufacture a reason to invade. I posted a few months ago that I was concerned that Obama would try to manufacture a reason to invade Iran because he will need to do something with all the returning soldiers.