"Slay the idolaters wherever ye find them, arrest them, besiege them, and lie in ambush everywhere for them." (surrah 9:8)
I read one time that the 9/11/01 attacks were simply following the pattern of how Islam has traditionally waged war. Here is textual support in the Quran for "ambush" attacks "everywhere." That is not how Islam fought the Crusades, however. That is why Islam lost the Crusades. This is also why, for several years, I have urged "verbal provocation of Islam," like was done in Garland, Texas in June. Islam cannot resist verbal provocation, it will rise to the bait, and if we are prepared we boomerang the ambush strategy on them. Over the years I have done my part to verbally provoke Islam :)