WWII Atomic Bomb Project Had More Than 1,500 "Leaks"
fas.org
fas.org
Still, that's an amazingly small number of leaks for such a huge project.
The Manhattan Project (along with many other portions of the US government at the time) was in fact plagued by Soviet spies.
One could argue that Roosevelt was also taken in by uncle Joe to a lesser extent if you read the history of the various 3 power summits.
For a fascinating take on this I suggest the book See No Evil by Bob Baer. He talks a lot about his experiences as a CIA agent doing just that in a lot of interesting places during the cold war.
You can draw several analogies to computer systems and security products as well.
I'm about halfway through, well worth the (long!) read.
http://www.nytimes.com/books/99/09/19/specials/rhodes-dark.h...
Excellent read, highly recommended. First book I've had time to fit in in a long time and I'm really glad it's such a joy. There are many paragraphs that make you laugh quite unexpectedly.
[1] http://www.newyorker.com/magazine/2013/09/30/nukes-of-hazard
Right at the end of the book there is a few pages about Soviet systems, saying that there were always inherently safer, because no one trusted anyone,so they had launch codes and interlocking safety mechanisms pretty much from the very beginning of nuclear age.
Would also very highly recommend that book.
"the Soviet Union had deployed 100 tactical nuclear weapons to Cuba, and the local Soviet commander there could have launched these weapons without additional codes or commands from Moscow"
http://en.wikipedia.org/wiki/Cuban_missile_crisis
http://en.wikipedia.org/wiki/Vasili_Arkhipov#Involvement_in_...
The historical docs themselves are at https://www.osti.gov/opennet/manhattan_district.jsp.
Seriously. The Manhattan project involved 130,000 people at its peak and lasted four years, and it leaked.
The Apollo program involved 400,000 people at its peak and lasted eleven years.
I don't believe it was a conspiracy, but I also don't think that there's a fundamental reason why it definitely couldn't have been.