If you look at documents at the time, intelligence agencies said there was a possibility he had WMDs, but there was no conclusive evidence nor assurances.
The Bush Administration lied to Congress and said we knew for sure they had them.
Edit: It’s good to have healthy skepticism – it hasn’t escaped my notice that the majority of evidence behind this claim is coming from Israel. I don’t think it’s wise to deem it automatically false however, and pulling funding is premature. There should however be a serious internal investigation. And if they already have smoking guns, the UN should release them in the interest of transparency.
Apologies for starting out my comment as a bit of a jackass.