How to keep the bomb from terrorists

According to Graham Allison of Ploughshares-funded Belfer Center at Harvard, the science of nuclear forensics, which entails tracing the materials from a terrorist event to their source, is key to a new nuclear deterrence. Experts are assembling a database of all known sources, but Allison cautions that the ability to identify the source of nuclear material is not enough.  He recommends a new organization called the Global Alliance Against Nuclear Terrorism to minimize the risk of such terrorism, requiring members to take every action possible to prevent nuclear weapons or materials from being obtained by terrorists.