I had never seen the 500 ton amount in Iraq. I would have used it as ammo against the WMD deniers.
With regard to the rest of the WMD claims, I've always suspected that we didn't *want* to prove that there were chemical and biological weapons anywhere in the the thousands of munitions depots spread around Iraq. Do that, and suddenly its a race against time to find them before Al Queda does.
When the story of no-WMD was being reported, it was only days after the fall of Baghdad. We didn't even know where all the munition bunkers were yet.
Beats me... but I want dibs on the credit if it is ever declassified. :-)