matthew bunn, an expert on nuclear proliferation issues at the john f.nedy school of government at harvard university joins us to explain the day's developments. so what led up to this handover and, in fact, if they were so insecure about this material, what took so long? >> this is something the united states has been talking about with japan for some years and i wouldn't say that it was very insecure in japan. there have been some important security improvements there in recent years. after the 9/11 attacks, they added armed guards at this site, there have been more significant security improvements quite recently, but this is really a tremendous step forward, this is some of the best material for terrorists if they can get their hands on it that exists in states without nuclear weapons and now we're going to be getting rid of it entirely. it's material that's merely the same stuff you would get if you broke into a nuclear weapons facility but not the same kind of security that exists at those facilities in the united states. >> they also asked today t