With the tactics being top-secret I doubt there would be a lot of documented cases of it happening that could prove it exists - that would kind of defat the whole purpose of it being secret. It would probably take another Snowden to get any evidence on it.
Hard to say as they don't talk. It would be bad for the US for them to admit success in cases like this. Not to mention admitting success puts attention on finding their spys.
It would be hard to prove with the existing leaks, but there are certainly forms of information that could be considered very valuable to and likely to incite known terrorist groups, no? I'm thinking things like detailed floor plans for embassies, personal info about members of the special forces, confirmations of extralegal executions and details of the people who carried them out, etc.
So far it seems no-one who has leaked information has had the clearance to get to the truly painful stuff, but the psychological screening to get to those levels is specifically designed to keep potential Snowdens and Mannings out.
Nope. While they may have a case against the original leaker, once it's out, classified information is out in the United States (not so in the UK, with the Official Secrets Act) and further disclosure is at least nominally protected by the Constitution.
That would work out very badly. Consider this cold war example:
Somebody high-up in the CIA is secretly working for the USSR. They are passing everything to the USSR. Over in the USSR there is a similar situation, with somebody passing KGB things to the CIA. The guy secretly working for us is able to reveal the person secretly working for the USSR.
Now we grab the person. If we reveal the evidence to him and everybody in unclassified court proceedings, it will get back to the USSR. Our agent in Moscow will be caught. Even if we black out his name, he will be caught. It's a scary enough risk just acting on the info he supplied.
Your way of doing things gives us 3 terrible choices:
a. Evacuate our super-valuable guy from Moscow.
b. Get our guy in Moscow killed.
c. Let the spy go unpunished, thus encouraging others.
Is there any evidence that low-level people have been targeted, or is this just speculation around what could happen?
Yes, "evidence for a secret program" is a bit tricky to produce, but the one I know of - Doe v. Ashcroft - the president of the company was compelled to produce data. I'd be very surprised if this wasn't the universal approach.
No verifiable evidence is presented because it shows your hand. If you show the enemy what you don't know, they could figure out what you weren't able to find out, and use that to their advantage. If they can trace the evidence back to a particular source, they can crack down on it and prevent future evidence from being collected through that pipeline. At best this means they change their security procedures, at worst it means they murder your spies.
I would guess that many times the evidence is from NSA signals intelligence and they can’t show their work because it’s classified. We end up just having to take their word for it.
this is such a wild scary thought. I'm pretty sure 100% some secret govt agencies underground in many countries would have tried it and sealed the records due to catastrophe.
When everyone involved has been explicitly been trained and selected to work with secrets, in a historical period when such activities are extremely dangerous and brutal, and under the treath of expedite death penalty or assassination... it's not that hard to believe any involved party would keep very silent.
The 'enemy' would have a very hard time figuring out which parts of the leaked documents were not leaked on purpose.
Distrust alone of any and all information would significantly limit any direct risk due to being named in a document helpfully supplied by your adversary, or at least people in the same general geographical area. And for all we know that's exactly what happened.
You can’t seriously expect intelligence gatherers to disclose something like that to the general public. It would become worthless. They’d never be able to use it again.
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