Can you (or a populace) be influenced by something you are unaware of? If so, you can be a victim of an act terrorism without knowing of the act.
If a terrorist shoots my sister, and nobody knows it was a terrorist plot, the destabilization and other negative effects are still there. I will be afraid, perhaps not of ISIS, but I will generally be terrified that someone might shoot me too.
Terrorism is not so simple. Thinking that all terrorism must be some extreme, singular act seems short-sighted. What is the terrorist's goal?
Terrorism can be subtle and long-term.
Edit: What terrifies you? Did terrorists exclusively create this (threat of terror)? My point is, does a terrorist exclusively create terror... or do these terrorists have a broader goal beyond simple terrorism?
> Surely there are successful terrorist plots that have succeeded that we are unaware of.
No. Terrorists even take credit for things they had nothing to do with. The goal of a terrorist is to strike fear into the population by committing crimes in the most public way possible. Secrecy of the result doesn't serve this goal. The other reason to publicize is for recruiting purposes.
We certainly know the number of successful plots. Failed plots and fizzles, perhaps not.
Thanks for the link (I love gwern). Terrorist organizations are always evolving though. For example, the ongoing PR campaign by ISIS. The PR is creating terrorists but there is never a singular attack. I would say the PR campaign is successful, but many people are unaware of it, compared to 9/11.
My point is, terrorism is not exclusively a single, concentrated moment of terror. Some terrorist plots are more subtle and long-term.
Do we? Are all terrorist plots obvious? Surely there are successful terrorist plots that have succeeded that we are unaware of.
I am saying, I doubt it's so black & white.