To answer the question of how to prevent terror:
The way to curtail terrorism has not changed.
Terrorism, for that matter, has not changed either. It has always been hard to find the culprits amongst the innocent civilians, and the civilians have always been the targets. They way you stop terrorism is by using technology to ensure surveillance of terrorist groups. The technology exists to listen to every person in the country, and they do it! Intelligence won us the cold war: is Al Qaida that much more advanced than the Soviet Union?

So why, then, do we even have to ask how to stop terrorism? Because we've been confused; we've been messed with. Our reaction to 9/11 was exploited, and we were made to believe that starting a war in Iraq was the best way to secure ourselves against terrorism. When this failed (miserably) we asked ourselves what will work.

The answer was always there, and it still is. We must use technology to keep an eye on terrorist organizations. You cannot plan something like 9/11 if the government is listening to every word you say.