The US and UK used the justification of imitate threat of attack from Iraq for initiating war the 2nd Gulf War. They had phrases that they repeated. “regime change” and so on. This attack would be especially dangerous because Iraqi weapons were known to be especially lethal and they had a history of using chemical weapons. This threat was named WMD. So people say because weapons of mass destruction were not found, that the justification for the 2nd Gulf War was negated.
It is important to remember that The United States and Great Britain are leaders in the arms trade and their relationship with Iraq was warm after the revolution in Iran. It is quite likely that they provided Iraq the weapons they are searching for. Iraq was a western ally in the region until its invasion of Kuwait in 1990.
There is a poorly remember joke, “We know they have weapons of mass destructions, we still have the receipts.”