and a substantial amount of chemical high explosive could, within several weeks, design and build a crude fission bomb. By a "crude fission bomb" we mean one that would have an excellent chance of exploding, and would probably explode with the power of at least 100 tons of chemical high explosive. This could be done using materials and equipment that could be purchased at a hardware store and from commercial suppliers of scientific equipment for student laboratories.

The key persons or person would have to be reasonably inventive and adept at using laboratory equipment and tools of about the same complexity as those used by students in chemistry and physics laboratories and machine shops. They or he would have to be able to understand some of the essential concepts and procedures that are described in widely distributed technical publications concerning nuclear explosives, nuclear reactor technology, and chemical explosives, and would have to know where to find these publications. Whoever was principally involved would also have to be willing to take moderate risks of serious injury or death.

Statements similar to those made above about a plutonium oxide bomb could also be made about fission bombs made with high-enriched uranium or uranium–233. However, the ways these materials might be assembled in a fission bomb could differ in certain important respects.

We have reason to believe that many people, including some who have extensive knowledge of nuclear weapon technology, will strongly disagree with our conclusion. We also know that some experts will not. Why is this a subject of wide disagreement among experts? We suspect that at least part of the reason is that very few of the experts have actually spent much time pondering this question: "What is the easiest way I can think of to make a fission bomb, given enough fission explosive material to assemble more than one normal density critical mass?" The answer to this question may have little to do with the kinds of questions that nuclear weapon designers in the United States, the Soviet Union, the United Kingdom, France, or Peoples Republic of China ask themselves when they are trying to devise a better nuclear weapon for military purposes. But the question is likely to be foremost in the mind of an illicit bomb maker.

Whatever opinions anyone may have about the likelihood that an individual or very small group of people would actually steal nuclear materials and use them to make fission bombs, those opinions should not be based on a presumption that all types of fission bombs are very difficult to make.