Scott Ritter (the former Marine, top aide to Schwarzkopf, Iraq weapons inspector, lifelong Republican, knew there were no WMDs *before* we invaded, branded a traitor by the Bushies, that Scott Ritter) has weighed in on this question:
The 2002 national security strategy—which the Bush administration used as a blueprint for initiation of a policy of… regional transformation in the Middle East—only mentioned Iraq once, and yet it was used as a document to set forth the events that led to the invasion of Iraq. The 2006 version of this mentions Iran 16 times as the No. 1 threat to the security of the United States of America. And it does not reject a preemptive war of aggression. In fact, in addition to not rejecting it, or not ruling it out, it embraces it; despite how bad things have gone in Iraq, it continues to say this was the right thing to do. Left with that, I don’t think anyone could question the motivation of the Bush administration, which is to continue with regional transformation policies in the Middle East that revolve around regime change, which means that’s what our goal is vis-à-vis Iran.
That’s why when I speak of Iran, I say be careful of falling into the trap of nonproliferation, disarmament, weapons of mass destruction; this is a smokescreen. The Bush administration does not have policy of disarmament vis-à-vis Iran. They do have a policy of regime change. If we had a policy of disarmament, we would have engaged in unilateral or bilateral discussions with the Iranians a long time ago. But we put that off the table because we have no desire to resolve the situation we use to facilitate the military intervention necessary to achieve regime change. It’s the exact replay of the game plan used for Iraq, where we didn’t care what Saddam did, what he said, what the weapons inspectors found. We created the perception of a noncompliant Iraq, and we stuck with that perception, selling that perception until we achieved our ultimate objective, which was invasion that got rid of Saddam. With Iran, we are creating the perception of a noncompliant Iran, a threatening Iran. It doesn’t matter what the facts are. Now that we have successfully created that perception, the Bush administration will move forward aggressively until it achieves its ultimate objective, which is regime change.
The whole interview is worth reading: