Chemical warfare

Botulin toxin has always been considered an inferior agent for chemical warfare since it degrades rapidly on exposure to air, and therefore an area attacked with the toxic aerosol would be safe to enter within a day or so. In fact, the agent is so unstable that the medicinal form is generally shipped on dry ice. There are no documented cases of the toxin actually being used in warfare; however, it has been claimed to have been used in the Operation Anthropoid to kill top Nazi Reinhard Heydrich and in "Operation Mongoose", where in 1961, the CIA saturated some cigars, of Fidel Castro's favorite brand, with botulinum toxin for a possible assassination attempt. The cigars were never used, but when tested years later were found still effective. The notorious Japanese biological warfare group Unit 731 fed botulinum to prisoners during Japan's occupation of Manchuria in the 1930s.
There has been concern over the use of botulin toxin as a terrorist weapon, but it appears not to be ideal for this purpose. The vials used therapeutically are considered impractical as weapons because each vial contains only an extremely small fraction of the lethal dose. Nor is home-growing very viable; the bacterium in question is anaerobic and grows poorly in the presence of oxygen. This would make it difficult for terrorists to produce the toxin in bulk without specialized microbiological expertise.
The toxin's properties did not escape the attention of the Aum Supreme Truth cult in Japan, who had set up a plant for bulk production of this agent, though their subway attacks used the nerve agent sarin instead, because of its easy dispersal and faster-acting properties.
It has been recently revealed that the CIA made attempts to assassinate Fidel Castro with several Botulinum Toxin pills placed in his drinks. The attempts failed when the operatives asked out of the operation.