Thats the military problem with terrorism... if you don't actually bring your target to their knees they are in all likely hood going to hit you back hard.

Pearl Harbour... Aircraft Carriers were not there. So although a horrific attack all it did was galvanise support against the Japanese.

Or if someone hits another guy in the groin... you had better hope you knock the wind out of him, because if he gets up he will rip you apart in anger.

So terrorists can't really reveal who did it... because they would get ripped apart, at the same time if they don't ante up they lose the whole point of attacking. Terrorism often works better when it is lower scale and less horrific, it is the gradual drip, drip, drip that will get change. If the opposite occurs then all it does is back people into a corner.