The correct response is to challenge the questioner about what the questioner now “knows” about Iraq. That would elicit either a lot of fumbling or a load of BS that is easily disproven.
If he had any savvy, he would have said “That’s a very understandable question and something I’ve given a lot of thought to and...” then debunk her question and assumptions with some well thought-out responses.
He looked like a fool while he was fumbling to try to compose himself.