The first two times the lonely little shepherd cried wolf, the villagers came running only to find that there was no wolf. The third time there was a wolf, but the villagers were suspicious and tired. They didn't come, and the wolf ate all the sheep and then the little boy.
Imagine how surly the villagers would have been if they'd had to run from Des Moines to Baghdad. They probably wouldn't have run the second time. So it'll be interesting to see how we villagers respond to Bush & Cheney crying "Iran! Iran!" every time something blows up in Baghdad.