On 14 January 2005, ten heads of government from Europe and North America and the Director General of the World Health Organization (WHO; Geneva, Switzerland) were scheduled to meet for a 'Transatlantic Security Summit' in Washington, DC, USA, to discuss the threat of international terrorism. On the eve of the meeting, news broke that citizens from several European countries appeared to have become ill with smallpox; shortly thereafter suspected smallpox cases appeared in the USA. Although the assembled leaders did not know it at the time, a radical terrorist group had obtained seed strains of Variola major—the virus causing smallpox—and deliberately released the virus in a number of main transport hubs and sites of commerce throughout Europe and North America. On 14 January, the heads of states who gathered in Washington were confronted with one of the worst nightmares imaginable: the use of contagious and deadly disease as a weapon.