I have to ask: If they have not conducted an attack, how was it determined that they were a terrorist?

Edit: A link to an example might be helpful.

It is difficult to determine the efficacy of this strategy although of course it results in successful terrorist arrests.

There are others.

This is a good start on the terrorist attack cycle and the surveillance techniques that are used. One of the problems with defense is that you had to protect against all possible attacks, and that includes people conducting on the ground surveillance.

As you suggest, more sophisticated groups will find better means of gathering the intelligence they need. Unfortunately, that still leaves crappy groups that don't know any better. Surveillance remains the best time to catch terrorists.

I can't speak to the specific example in the article, as usual the US is paranoid and over reacts, but the fundamentals are solid. Look for people conducting surveillance to catch terrorists.

Do you have any specific examples of terrorists who photographed their sites before attacking? I don't think there is much information that a terrorist couldn't get from a combination of watching and jotting things down in a notebook, and google street view + image search.

[1] http://www.theguardian.com/technology/2008/jun/05/news.terro...

Here's a reconnaissance manual: http://ruckus.org/article.php?id=809

In general, blacklisting or whitelisting specific techniques is not the path to security. Looking for people conducting surveillance activities around targets is a good way to catch terrorist plots before they execute. The alternative, catching them after they execute, is not particularly good.

This is completely different from a public landmark in the US which for which you will easily be able to find hundreds or thousands of photos from every conceivable angle.

I've still yet to see any evidence that overt photography or a public landmark would be useful to a terrorist, or any evidence that this has actually happened with enough frequency to classify photographing landmarks as suspicious behavior, or for that matter ever happened at all.

I'm not denying that terrorists conduct surveillance. What I'd like to see is evidence that they do so through overt photography of public landmarks and buildings.

> "If it helps, several terrorists have been caught due to conducting surveillance."

Which? And how did they react when the FBI agent left them his business card so they could have a chat on the phone?

First, an actual terrorist would probably have left as soon as the guards came out, rather than argue with them over whether or not photography from public property is allowed. Staying and arguing gives the guards more time to note identifying details that could lead their plans being disrupted.

Second, since they tracked him down from his rental car, and since they FBI does in fact have basic competence, they knew by then that he was a professional photographer and everything about the incident was consistent with his expected behavior based on his profession and his publication history.

So why not drop it at that point? My guess is they just wanted to make sure it really was him who rented the car in his name. A smart terrorist would use a fake identity to rent the car, and what better than to use an identity of someone who you would expect to find out photographing things like their target?

It's a little odd that they would worry at all about the photographs, the government aerial photos there are very high detail:

https://www.google.com/maps/@42.3009201,-71.0456476,291m/dat...

(there's 3 zooms left)

Looking at the layout, he was probably on that little drive that parallels the freeway (that's where the nicer photo is), and it probably isn't a public street.

edit: Looking at Street View, he must have been somewhere on Victory, that drive is gated.

another edit: The aerials in 2004 probably would not have been quite so detailed. But they would still be pretty detailed.