Saddam considered the Iranians to be a strategic threat to Iraq and discounted the possibility that the West & UN would act against him in a forceful manner. As a result Saddam had his government continue to act as if they still had WMDs to fool the Iranians after they had secretly disposed of their VX nerve gas after previous fooling the inspectors. (It sounds stupid, but that was Saddam.) Saddam's strategic deception was such a success that he was invaded for it.
That was not the reason for the invasion, it was a political decision, that was merely the excuse for the decision. That is all beside the point, I was referring to the report that the UK Government revealed to the Members of Parliament and the UK people to justify the war, all the cautions that the security services had about the evidence were removed. Alistair Cambell, Tony Blair's spin doctor was heavily involved in that process, despite having no knowledge of either the security services or WMD.
If it makes you feel any better, there were unfilled chemical warheads found for Iraq's long range missiles. With a native chemical industry that had previous experience making chemical agents they could have been filled in the future. The disarmament agencies also recovered a number of anthrax bombs. I'm sure there is more. And the other causes of action were still true, such as the massacres of the Kurds - a crime against humanity, and Iraq's support for terrorism.
Yes, the remnants of Chemical weapons were found, all of which dates from the 80's and early 90's, and all of which tallied with the UN Inspectors reports about them decommissioned in the mid 90's (from memory I see to recall 1995). am aware of the Anfal pogroms, then again I was aware of them in the late 1980's, but as prior to the invasion of Kuwait, Saddam was the West's "friend" in the region, that was ignored by the Western governments, as were the reports that he used chemical weapons against the Iranians during the Iran Iraq war.