[SteamshipTime]

If that were the case, they'd leave a calling card to publicize their success. The terrorist's whole purpose is defeated if he or she acts covertly.

[Savage Beast]

"If that were the case, they'd leave a calling card to publicize their success. The terrorist's whole purpose is defeated if he or she acts covertly."

I'm not so sure. I suspect that covert terrorist attacks were carried out before September 11 and have not yet been fully recognized as such--e.g. unexplained plane crashes, "accidental" deaths, et al. Terrorist attacks could (and perhaps did) remain covert as experimental preparations for future attacks, to eliminate specific individuals, or for other reasons. Furthermore, claims and boasting could follow at some later time.