For over 70 years, scientists, by dint of their unique ability to inform policymakers, have occupied a special position in driving the ways governments treat nuclear secrets. Enrico Fermi went so far as to write, "secrecy was not started by generals, was not started by security officers, but was started by physicists." He was undoubtedly thinking of Leo Szilard, who, having conceived of the chain reaction in late 1933 and later reported it in a 1934 patent application, promptly assigned it to the British government to be kept secret. In many ways, Fermi did not exaggerate: Szilard's first attempt to assign the patent was rejected by the War Department, which saw no harm in disclosing his insight.
In the early days, when no one was sure how widely known the basic principles of the bomb were, blanket secrecy was a sensible approach. Indeed there are still prohibitive risks involved in releasing many nuclear secrets. Today, though, the balance is different. Scientists and military experts, through more than half a century of experience, are now far more capable of distinguishing between dangerous and benign releases of information. At the same time, an increase in global exchange and international cooperation has raised the value of shared information, not only within the nuclear sphere, but with respect to national security measures more generally. Moreover, Cold War experience has taught us that sharing some information with enemies can help shape their behavior in useful ways.