Remember the Maine! Yes, the Maine was an American ship burned in Havana harbor, which was the pretext for attacking Spain to get Cuba and the Phillipines from them -- and to eject them from the American "sphere of influence" in the western hemisphere. So we burned our own ship and blamed them for it so we'd have an excuse to attack them.
Remember the Gulf of Tonkin! This was the incident in which the North Vietnamese supposedly fired upon an American ship off the coast. Thus attacked, Americans felt justified and morally obligated to "defend themselves" against such "unprovoked aggression." It is now clear to even mainstream historians that this incident never actually occured and was wholly fabricated by the American administration as a pretext for attacking North Vietnam.
Nothing changed on 9-11. It's the same old story of audacious lies being used to justify nefarious deeds. If you dare to doubt the comforting bullshit, check out this film: