From his newsweek interview:
Well, it’s extremely difficult to talk about this because of a very rigid doctrine that prevails in the United States and Britain which prevents us from looking at the situation realistically. The doctrine, to oversimplify, is that we have to believe the United States would have so-called liberated Iraq even if its main products were lettuce and pickles and [the] main energy resource of the world were in central Africa. Anyone who doesn’t accept that is dismissed as a conspiracy theorist or a lunatic or something. But anyone with a functioning brain knows that that’s not true—as all Iraqis do, for example. The United States invaded Iraq because its major resource is oil. And it gives the United States, to quote [Zbigniew] Brzezinski, “critical leverage” over its competitors, Europe and Japan. That’s a policy that goes way back to the second world war. That’s the fundamental reason for invading Iraq, not anything else.
I think Chomsky is slightly off on his analysis of the ‘rigid doctrine’: I think you were perfectly able to admit in civilized discourse that part of the reason we invaded Iraq was its oil reserves, you just can’t do that while maintaining that this fact has any moral relevance. This isn’t really based on any detailed thought about the situation, I just feel like I heard a lot of people (even within the media) talk about how we were involved in part because of the oil, but I agree with Chomsky that you never heard anyone prominent act as if that made any difference to the justification of the invasion.