Iraq admitted to the United Nations in 1995 that it loaded anthrax spores into warheads during the Gulf War. In the post-cold war era, the former Soviet Union admitted to having enough anthrax on hand to kill every person on the planet several times over. The accidental aerosolized release of anthrax spores from a military microbiology facility in Sverdlovsk in the former Soviet Union in 1979 resulted in at least 79 cases of anthrax infection and 68 deaths and demonstrated the lethal potential of anthrax aerosols. Members of Aum Shinrikyo, the group responsible for the 1995 Tokyo sarin attack, reportedly experimented with biological agents in Japan before resorting to chemical agents. Fortunately, no one was injured in these events.
Anthrax is, by far, the easiest biological agent to produce and weaponize.
Production of anthrax as a biological weapon does not require special equipment or advanced technology. It is extremely stable and can be stored almost indefinitely as a dry powder. It can be loaded in advance, as a freeze-dried powder, in munitions or disseminated as an aerosol with crude sprayers. While protective clothing and gas masks provide excellent front-line defense, their effective use requires rapid and early detection of the agent. Detection devices are not sufficient to completely protect against the threat.