Here is an AFP report taken from WikiLeaks about a statement made by Robert Gates, Secretary of Defense:

The American defense secretary told Morin that he "believed a conventional strike by any nation would only delay Iranian plans by one to three years, while unifying the Iranian people to be forever embittered against the attacker," it said.

Q: Barbara Slavin

If I could do one more.  What do you think would be the reaction of the Iranian people if the United States would use military force against Iran despite their dislike, contempt, anger at the regime. Do you really think that the Iranian people would welcome being attacked?

RK

Well, again this is based on what I know, and what I felt. This is another thing that MOIS lobbies have been selling to America for a long time. That if you attack Iran the people of Iran are going to unite behind their rulers and defend them to the end of time. Let me say it very clearly now: People of Iran are dying. They are being beaten in the streets for walking slowly. They are being given demands for haircuts, or how you can walk, or how you can talk. They are being taken to Even prison and other places, tortured and executed. They would love for you to take these, and I am not going to use that word, to take these people out. There was a saying during the time of 9/11 when America attacked Afghanistan, that Iranians were on the rooftops saying, this way please. They have been saying this way please for thirty years and you have failed to understand that. So if there is a military action, I would highly suggest that please do not take out the infrastructure, do not hurt the Iranian people, do not bomb the heck out of Iran, they are your allies, they are your friends. Take out the Revolutionary Guards. We know of every base of every location. You can carry out a week of severe bombings of the Revolutionary Guards and at the same time vocally announce your support for the freedom of Iran, and the people would do the rest.