Nothing

What did Iraq have to do with 9/11? Nothing. We got it from the chimpanzee's own mouth:

BUSH: You know, I've heard this theory about, you know, everything was just fine until we arrived and -- you know, the stir-up-the-hornet's- nest theory. It just doesn't hold water, as far as I'm concerned.

The terrorists attacked us and killed 3,000 of our citizens before we started the freedom agenda in the Middle East.

QUESTION: What did Iraq have to do with it?

BUSH: What did Iraq have to do with what?

QUESTION: The attack on the World Trade Center.

BUSH: Nothing. Except it’s part of — and nobody has suggested in this administration that Saddam Hussein ordered the attack. Iraq was a — Iraq — the lesson of September 11th is take threats before they fully materialize, Ken. Nobody’s ever suggested that the attacks of September the 11th were ordered by Iraq.

Note that Bush STARTS by making this sort of assumed equation between Iraq and 9/11, and then has to back off.

"Nobody has suggested in this administration that Saddam Hussein ordered the attack," my ass. He just DID.