Botulism has been used as a weapon of terror in the past. During World War II, the infamous Unit 731, the Japanese biological warfare group, fed cultures of Clostridium botulinum to prisoners during the Japanese occupation of Manchuria, killing them. It was suspected that Germany had weaponized botulism as well, and several other countries were suspected to have done research into the use of botulism as a weapon. More recently, between 1990 and 1995, aerosols were dispersed on at least three occasions by the Japanese cult Aum Shinrikyo, who would later go on to release sarin gas in the Tokyo subway, to disastrous effect. These releases of botulism failed for various reasons, but the ease with which Aum Shinrikyo was able to culture Clostridium botulinum from the soil is one reason that this toxin would make an excellent bioweapon.