Editor's note: Conscious of the controversial nature of this article, Technology Review asked Allison Macfarlane, a research associate in the Science, Technology, and Global Security Working Group in MIT's Program in Science, Technology, and Society, to rebut its argument: see "Assessing the Threat." We were also careful to elide any recipes for developing a biological weapon. Such details as do appear have been published before, mainly in scientific journals.

Last year, a likable and accomplished scientist named Serguei Popov, who for nearly two decades developed genetically engineered biological weapons for the Soviet Union, crossed the Potomac River to speak at a conference on bioterrorism in Washington, DC.