"Iraq's intransigence and deceptive practices during the periods of UN inspections between 1991 and 2003 deepened suspicions among many world governments and intelligence services that Baghdad had ongoing WMD programs. Ironically, even at key junctures when the regime attempted to partially or fully comply with UN resolutions, its suspicious behavior and destruction of authenticating documentation only reinforced the perception that Iraq was being deceptive. [...] Early 1990s concealment activity combined with unexpected revelations following Husayn Kamil's defection led analysts to view Iraq as a sophisticated D&D [denial and deception] practitioner. Faced with inconclusive or uncertain data, analysts made judgments with conviction that Iraq could successfully conceal damaging data. [...] We recognize that portions of our data were supplied by the same people who were responsible for the deception campaign and provided insight in captivity. Captured documentary evidence exploited to date so far supports the conclusions of this paper."
The National Security Archive: http://www.gwu.edu/~nsarchiv/