> Well, no German or Japanese spies, which were presumably the primary worry at the time. Funnily it seems it was not! My source is a book titled "Restricted D

> Well, no German or Japanese spies, which were presumably the primary worry at the time. Funnily it seems it was not! My source is a book titled "Restricted Data" by Alex Wellerstein which chronicles the history of nuclear secrecy in the USA. It really seems that at least initially the biggest worry for those tasked to maintain the security were leaks to Congress/Senate. It seems there was a worry that if the wrong politicians get wind of the project they will shut it down. After all they spent a lot of money on something which sounded like a bad scifi at the time.