trevor paglen has written/spoken about this topic extensively, e.g. http://www.amazon.com/Could-Tell-Then-Would-Destroyed/dp/193... from 2007 and various talks on youtube, e.g. from 30c3: https://www.youtube.com/watch?v=HTVgPw7TR_k

There's a whole book, titled I Could Tell You But Then You Would Have to be Destroyed by Me: Emblems from the Pentagon's Black World: http://www.amazon.com/Could-Tell-Then-Would-Destroyed/dp/193...