You have touched on a very important point. I sometimes think that after the terrible events of 9/11, 7/7 in Britain, and so on, part of the cry that went out was for information sharing über alles. If we just broke down all the walls and shared all our information, the world would be a safer place.
I don't agree with that. I frankly believe that walls and differences are important, and our country should be prepared to exchange, for intelligence purposes, information--properly controlled and reviewed when you know what it's going to be used for--that you would not be prepared to share for law enforcement or enforcement purposes.
The intelligence world deals with and in the world of suspicion, as you say. We often ask, “What do you know about...? Has this person come across...?” and you don't want someone to do something about it. You don't want someone to take action or make life difficult for someone. You simply want to put together the pieces of the puzzle. It's terribly important that the same information you might want to exchange for some purposes, you might not want to exchange for different purposes.