Since the anthrax attacks of 2001 in the United States, annual U.S. government spending on biodefense programs has increased enormously. U.S. biodefense was once exclusively the domain of military agencies and was aimed principally at protecting battlefield troops against the products of state-run biological warfare programs. Today, it is engaged in and promoted by a variety of government agencies contemplating “bioterrorism,” and it is aimed principally at protecting the American civilian population. I ask if certain U.S. biodefense policies, pointedly those funding “threat assessment” projects, make biological attacks paradoxically more likely by undermining international norms against deliberately causing disease. I conclude that they do and consider the ramifications of this answer.