You're technically correct in that chemical weapons were found, but the bigger picture is that that these were manufactured before 1991. Also, the US government

You're technically correct in that chemical weapons were found, but the bigger picture is that that these were manufactured before 1991. Also, the US government itself deliberately suppressed knowledge of these findings because they made the "active WMD programme" basis for going to war look even more dubious. All of this is mentioned in the linked article.