Washington: Sarin gas, which cripples the nervous system, was first produced by Nazi scientists in the 1930s and used in two attacks by a Japanese cult in the 1990s. Even a tiny dose can be deadly.

The most notorious sarin attack occurred in 1988 in the village of Halabja in northern Iraq, when as many as 5,000 Kurds were killed and 65,000 injured when the Iraqi military used a combination of chemical agents including sarin, mustard gas and possibly VX.

A radical Japanese cult used sarin in the Tokyo subway in March 1995 to kill 13 people and injure 6,000 others.

Syria’s programme was launched in the 1970s with help from Egypt and later from the former Soviet Union. In the 1990s, Russia lent a hand, followed by Iran since at least 2005, according to the independent Nuclear Threat Initiative.

The Scientific Research Council in Damascus appears to be directing the Syrian chemical weapons programme, the NTI said.

The US Congressional Research Service pointed to accessible information suggesting that the production and storage of nerve gas and mustard gas is concentrated in and around the cities of Al Safira southeast of Aleppo, Damascus, Hama, Homs and Latakia.

Delivery vehicles include Scud ballistic missiles and launch systems, along with aerial bombs and shells, according to publicly-available information.

However, “there is not sufficient information in open sources to draw any conclusions about the security of Syria’s CW arsenal,” the NTI warned.

Treaties

Several international agreements have sought to limit the use of chemical weapons in warfare, beginning with the 1675 Strasbourg Agreement that banned the use of poison bullets in conflict. More recently, a United Nations initiative led to the signing of the Chemical Weapons Convention in 1993. The convention, which has been signed by 182 states, enforces a comprehensive ban on developing, producing, stockpiling and using chemical weapons. Syria is not among the signatories to the Convention and thus is not legally bound by its prohibitions.

Chemical weapons include a wide variety of warfare agents developed specifically for military use, in addition to toxic industrial and commercial chemicals such as chlorine and phosgene and chemical toxins of biological origin such as ricin.

Bulletted box

Here’s a look at the ways chemical weapons have been used militarily in recent history:

First World War: Chlorine and phosgene gases were released on the battlefield. The first large scale attack with chlorine gas took place at Ieper in Belgium on April 22, 1915. Ninety thousand people were killed and more than a million injured as a result of the use of chemical weapons in the war.

1980s: Iraq used chemical weapons against Iran in their eight-year war. Iraq also used chemical weapons against Kurdish Iraqis in Halabja in 1988.

2004: US military used white phosphorus in Fallujah, Iraq.