Nearly as I can recall, they acted on bad intelligence info. That isn’t lying. There were many reason that we went into Iraq. The WMD were the least of it. Was it wise? In retrospect? Probably not. Obama made sure it would be a failure. The blame can be laid at his doorstep as well.
Bad intelligence, how about manufactured Intel.
We based a great deal of our reasoning on the intel of a guy code named Curveball, read this stuff on him: https://en.wikipedia.org/wiki/Curveball_%28informant%29
Just an example of what we were sold as the truth for WMD’s existing.