Astonishing and almost impossible to believe:
Rumor has it that when the clock in the town square of Prague was finished, the city leaders had the clockmaker’s eyes gouged out to prevent him from building something so beautiful for anyone else (http://en.wikipedia.org/wiki/Prague_Astronomical_Clock). I doubt we would have done that to our victorious scientists in any event, but I wonder if their confidence that it could easily be replicated did not create the very conditions – loose restrictions on scientists – that actually allowed the design to spread. At the very least, we might do a better job of making sure hobbyists don’t publish blueprints (http://www.newyorker.com/online/2008/12/15/slideshow_081215_atomicbomb), but since we never even killed Klaus Fuchs (http://en.wikipedia.org/wiki/Klaus_Fuchs), our weakness on the subject has been clear since the beginning.
In The Making of the Atomic Bomb, Richard Rhodes has the brilliant Niels Bohr plead with the simple-minded Roosevelt and Truman that the bomb design should be shared with Stalin; reverse-engineering it will be trivial, and think of all the good will you would generate by giving it to Joe. Nobel Prize or not, that proved to be massively incorrect.