Kolokol-1

According to Lev Fyodorov, a former Soviet chemical weapons scientist who now heads the independent Council for Chemical Security in Moscow, the agent was originally developed at a secret military research facility in Leningrad (now restored to its historic name of Saint Petersburg), during the 1970s. Methods of dispersing the compound were reportedly developed and tested by releasing harmless bacteria through subway system ventilation shafts, first in Moscow and then in Novosibirsk. Fyodorov also claimed that leaders of the failed August 20, 1991, Communist coup considered using the agent in the Russian parliament building. == Use during Moscow theater hostage crisis ==

Kolokol-1 is thought to be the chemical agent employed by a Russian Spetsnaz team during the Moscow theater hostage crisis in October 2002. At least 129 hostages died during the ensuing raid; nearly all of these fatalities were attributed to the effects of the aerosolised incapacitating agent that was pumped into the theatre to subdue the militants. The gas was later stated by Russian Health Minister Yuri Shevchenko to be based on fentanyl. Minister Shevchenko's statement followed speculation that the gas employed at the theater violated international prohibitions on the manufacture and use of lethal chemical weapons, and came after a request for clarification about the gas from Rogelio Pfirter, director-general of the Organisation for the Prohibition of Chemical Weapons. The minister stressed that the drug fentanyl used in the gas, which is widely used as a pain medication, "cannot in itself be called lethal". Shevchenko attributed the hostage deaths to the use of the chemical compound on the poor physical condition of the victims after three days of captivity - dehydrated, hungry, lacking oxygen and suffering acute stress, saying "I officially declare that chemical substances of the kind banned under international conventions on chemical weapons were not used," according to the Interfax news agency. This comment is disputed on two grounds. First, the United States Ambassador to Russia at the time complained that delays on the part of the Russian government in identifying the exact nature of the active agent in the gas led to many hostage deaths which might otherwise have been avoided. == Carfentanil ==

Carfentanil, one of the two fentanyl derivatives used in the Moscow theater hostage crisis was actively marketed by several Chinese chemical companies at the time. Carfentanil was not a controlled substance in China, where it was manufactured legally and sold openly over the Internet up until May 1, 2017, when a ban on fentanyl and all fentanyl analogues went into effect. The toxicity of carfentanil has been compared with nerve gas, according to an Associated Press article. The article quoted Andrew C. Weber, Assistant US Secretary of Defense for Nuclear, Chemical and Biological Defense Programs from 2009 to 2014 as saying "It's a weapon. Companies shouldn't be just sending it to anybody." Weber added, "Countries that we are concerned about were interested in using it for offensive purposes ... We are also concerned that groups like ISIS could order it commercially." Weber described various ways carfentanil could be used as a weapon, such as knocking troops out and taking them hostage, or killing civilians in closed spaces like train stations. == References ==