Complete tangent here, but a while back I came across a link to information on the M-388 Davy Crocket, a man-portable nuclear warhead that was actually deployed during the cold war. It's a nuclear explosive that can be fired from a recoilless rifle (a tripod mounted, crew-served weapon that took about 3 people to operate) and that was designed to use radiation to kill everyone in a .25 mile radius. The complete warhead weighted 70 pounds. They made 2,100 of these during the cold war. They were decommissioned decades ago.
Even though these are out of use, and were never used in combat, the idea is pretty freaky. I guess I've always thought of nuclear weapons as involving really big missiles from land or submarines, or dropped from planes. The idea of one of these that you could carry in a backpack, and that we actually made thousands of these in the 60's and 70's, scares me. You can see why people get so nervous about terrorists getting nuclear material when you see just how mobile this stuff can be.