I thought of all of this when I read the fascinating new book Spying on the Bomb by Jeffrey T. Richelson, a senior fellow at the privately funded National Security Archive and the author of other books on military intelligence. While some of this material has been available in other sources, it has never been put together so comprehensively. He has also interviewed some of the participants. The book begins with an account of US attempts during World War II to learn what the Germans were doing and goes on to describe its efforts to obtain information about the nuclear programs of the Iraqis, North Koreans, South Africans, Israelis, and Iranians. The one common theme is that if you do not have both agents on the ground and competent people to interpret what they have uncovered, you are playing a game of blindman's bluff with very high stakes indeed.

http://www.nybooks.com/articles/19010