Sarin

Sarin, also known by its NATO code of GB and O-Isopropyl methylphosphonofluoridate, is a lethal, nonpersistent chemical weapon, of the nerve agent family. It was first synthesized by Germany in World War II, but was not produced at the time as its manufacture was more difficult than that of Tabun (GA). After the war, it was stockpiled by the Soviet Union, United States, and other countries, although banned by the 1972 Chemical Weapons Convention and has been subject to national destruction programs. It was stockpiled, and used in the Iran-Iraq War, by Iraq, and may have still been in the Iraqi stockpile at the time of the Gulf War.

Delivery

National militaries stockpiled it in aircraft spray tanks, bombs, artillery shells and missile warheads. Unless the sarin was quite pure, and any excess, inflammable, isopropanol was removed, it could catch fire and degrade if dispersion was by an explosive warhead burster. Spray tanks, which were used by Iraq against civilians, are more efficient and more likely to work, although far more difficult to use against an enemy with air defenses.

Impure sarin also degrades fairly rapidly, and that was one of the reasons for developing binary munitions, in which the final two chemicals were mixed in an artillery shell or bomb, just before release. Iraq used a field technique in which a soldier, wearing personal protective equipment, would mix the final two liquids just before they were used to fill casings about to be launched. The reason that binary munitions were of interest to powers that could produce the stable agent was that the munitions were far less dangerous in storage.

It was used by the terrorist group, Aum Shinryo, in a 1995 attack in the Tokyo subway, and possibly in earlier, smaller attacks. Eight people died in the subway attack, but the death toll would have been far worse had it been even more slightly more efficiently dispersed. Aum operatives simply punctured plastic bags of the liquid chemical and relied on evaporation.

Counterproliferation

Sarin and its major precursors are explicitly listed in the Chemical Weapons Convention/Schedules and subject to international export controls for those that do not have extensive civilian dual-use, such as isopropanol. National controls vary; a BBC news investigation showed that in 2003, it was possible to buy the precursors within the UK.