In answer to you and others above who wonder why US gov policy is so anti-Iran: they, along with Assad to a lesser extent, are the foremost backers of Israel's number one threat, fellow Shiites, Hezbollah.
The Saudi's--the true financial supporters of all things Sunni-fundamentalist, including ISIS--have crafted a kind of tentative peace with Israel, based upon oil interests, fear and loathing of all things Shia and Iranian, and the US weapons and influence conduit that protects their current status.
In a region where there is no good side to be on, I tend to support Shia interests over Sunni-Wahabists. Iran is no bastion of freedom, but they stand out as clearly more modern than other power centers in the MidEast. When they reached out to us post-9/11, we should have grabbed the opportunity--Israel, however, would have been horrified.
Thomas Friedman, otherwise known as Israel's best rich-kid mouthpiece in Washington, is a shill for all things that back up the scenario I describe above. So, frankly, are Hilary and Kissinger. I have numerous qualms with Obama, but on this topic, he positioning was better than most in DC.