Is ISIS/ISIL really concerned with some grandiose plan like 911? Some of the 911 hijackers were fooled into doing a suicide operation, they thought it was a hijacking. That planning with fickle participants, is that in keeping with the dicipline that ISIS/ISIL displays?
They could just put four guys out in a car on a highway near you and start macine gunning the cars they pass. They might easily shoot up 50 cars before they run out of ammo or before they are stopped. That could happen any and it could happen again the next day -that’s effective terrorism.
Or, as we have seen they have very effective (masked) death squads. They could send their star death squad here, we can’t identify them. They may have no record under another Nationality. They could send a death squad with a senced pistol, and camera of coarse, to a Senator’s house, congressmen’s house, or better yet a celebrity. They could then easily slip away and post thier video. Again, that could happen any and it could happen again the next day -that’s effective terrorism.