I would not classify my comment as defeatist. By definition, Terrorism is action that exploits a society's freedoms to create terror. Thus any free society will be vulnerable to terrorism.

No matter what areas our government cracks down on, as long as we have any freedoms left, someone can exploit them to create terror.

You dismiss my point about low tech, low sophistication attacks. But think about how everyone reacted when mysterious (but eventually harmless) white powder was found in a few envelopes. Terrorism exploits freedom for great psychological effect.