It seems that Saddam Hussein allowed the world to believe the US claims that he had WMD, in order to deter Iran from launching an attack.
This at least is the view of George Piro, the FBI agent who interviewed Saddam after his 2003 capture.
Piro also claims that Saddam was surprised by the US invasion.
Piro is quoted in CBS 60 Minutes as saying:
"He told me he initially miscalculated ... President Bush's intentions. He thought the United States would retaliate with the same type of attack as we did in 1998 ... a four-day aerial attack.
He survived that one and he was willing to accept that type of attack."
Now the Iraqi people have to deal with the consequences of the errors of Saddam and the US.