1. Jonathan B. Tucker, PhD, is the Georg Zundel Professor of Science and Technology for Peace and Security at Darmstadt University of Technology, Darmstadt, Germany, and the author of Scourge: The Once and Future Threat of Smallpox. In 2008 he served on the professional staff of the Commission on the Prevention of Weapons of Mass Destruction Proliferation and Terrorism. This commentary is adapted from an article first published in the March 2009 issue of Arms Control Today.