Well, 9/11 had no connexion to Iraq, but Bush invaded anyway. I suppose he could invade based on the false WMD claims of OTL...Probably USA wouldn't attack to Afghanistan nor Iraq. There wouldn't be very good excuse. World probably even wouldn't care about nonexistent WMD's. United Kingdom might not be so intrested without 9/11 and Bush has probably bit more difficult get support. Bombings might continue but hardly more.