Anyone responsible who thinks about this stuff, even if they don't have a security clearance, will look into the question of what the ethics are and what the legal consequences of secrecy laws are if you talk about certain things you think about. I had dinner with a nuclear scientist at a conference, for instance, who told me that he hadn't told anyone else about his concern that Np237 was the material that terrorists would most want to steal from a commercial reprocessing facility (if they knew what we knew) and I told him it was no problem because people from Los Alamos had published a paper with specifics on that a few years earlier.

I will leave it at that.