This month's Scientific American has a good article by a pair of Princeton physicists concerning "HEU," highly enriched uranium. 25 kg (55 pounds) of HEU is enough to build a nuclear bomb. HEU's found in 140 civilian facilities--often poorly guarded--around the world. Khazakstan and Uzbekistan have between 100 and 1000 kg each, while Russia has over 10,000 kg. Russian nuclear scientists, often unpaid or underpaid, have already been caught stealing--no one knows how much HEU is missing. HEU is hardly necessary to nuclear power or research any more. New technology permits replacing it with LEU. As the article points out, however, we have been agonizingly slow to assist the world with this transition. The FY 2005 Bush budget for this activity was $70 million. At this rate, it will be 2014 and 2020 before various goals in the conversion and safety process are completed. Consider the vast expense--tens of billions of dollars--of the Bush/Reagan Star Wars plan, which, even if it worked (which is highly questionable), would defend us only against ICBMs. This defends us from the few places able to launch ICBMs. It seems much more likely to me that we'll be the victim of a bomb made from a few kilograms of HEU. The authors suggest that terrorists could simply smuggle a few kilograms of HEU into a building, improvise a gun-type detonation device of the type used in Hiroshima bomb, and blow a U.S. city to smithereens. We can't blame only the Russians. We ourselves gave HEU technology to countries around the world during the cold war. We owe it to ourselves to clean it all up now. Shouldn't we spend a few billion dollars and end this risk--which is perhaps the gravest risk we face? Why, after 9/11 showed that we're vulnerable, are we dawdling? Mariner.