Iraq an immediate and dangerous threat to the USA?
No air force
No navy
No long range missles
No way for any WMD to reach the US.
Suicide bombers are NOTWMD.
Hijacking a plane is not WMD.
Terrorism is not a WMD.
And none of those items present a significant enough of a threat to US security to warrent first strike actions. Retalitory attack, debateable.