Everybody knew Saddam had chemical weapons. He had already used them on the Kurds and Iranians. We didn’t go to war because Saddam had chemical weapons. This is no vindication for Bush. He blundered terribly in invading Iraq. Bush’s best service to the country was later ignoring the same voices who urged a war against Iran.
Well, in part. There were several reasons listed, of which WMDs were one. Not the main one, but one of the reasons.
I've always found it ironic that the UN-loving left got mad at Bush when he tried to enforce UN resolutions that the Iraqis were violating. (17 of them.)
But the main reason was that Iraq was supporting terrorists (including Al Qaeda) and that it was in violation of the 1991 ceasefire. All the other things were just extra reasons.
Iran would have been a better choice than Iraq or Afghanistan, in a way. They were supporting our enemies in both countries. Take down the mullahocracy and you take down the nerve center.