That's the first time I hear about nuclear weapons in this context - I was always under impression that this was about chemical weapons, which they found a lot of evidence of after the invasion.
Read the article I linked above. It's from that time period and Cheney and others specifically tried to link Iraq to nuclear weapons and Al Qaeda. It was fear-mongering and lying to justify the war and the Bush administration knew it: http://www.newsweek.com/2015/05/29/dick-cheneys-biggest-lie-...
I specifically recall LOTS of talk about "mushroom clouds" from the Bush administration leading up to the war. We knew they had chemical weapons because we sold them to them.