My straightforward opinion:
1.) Pentagon, our heroes' deaths (PA) and World Trade Center attacks: Terrorists was to blame as an act of war.
2.) Loss of WTC, the action to retaliate: attack terrorist systems, tactics and its allies.
3.) Communicating our retaliation: Any allies that fund, declare or provide terrorists their support, will be targeted. Saddam openly declared his support towards terrorists by providing the training ground for them.
Do the math.