There were WMD programmes initially - the precursor to UNMOVIC, UNSCOM discovered and destroyed equipment for making nuclear weapons during their inspections (calutrons, IIRC). In the years 1991-98 they didn't discover any Iraqi WMD at hidden (undeclared sites). They were, however, withdrawn as a result of Iraqi obstruction (denial of access, and helicopter overflights of sites to block U2 observation being examples).
To be fair, part of the Iraqi grievance was that the likes of the US, etc, had been using them (through bugging, etc) as an intelligence/espionage channel.