The great team at Nuclear Diner – a must visit blog for all of those interested in WMD issues – and I teamed up for a post on Syria’s chemical weapons program. This post will also appear on the Nuclear Diner site and was co-authored with Cheryl Rofer, a chemist who worked at the Los Alamos National Laboratory for 37 years, including on processes for the disposal of chemical weapons. (Check out Nuclear Diner for their daily WMD Specials!)
Last week there was a lot of breathless confusion in the news about Syria’s putative readying of chemical munitions. Specifics of observations were few, conclusions were many.
Let’s look at what those observations might have been. An important caveat is that there is not a lot of information available publicly on the Syrian chemical arsenal, and that may extend to Western intelligence services. Syria is believed to have mustard (a blistering agent), Sarin (a nerve agent, also known as GB), and VX (another nerve agent) in its stockpile. Sarin and VX can be prepared as binary agents and therefore are the focus of recent news reports.
A chemical munitions depot consists of processing and storage buildings and places to store the chemicals, likely bunkers or igloos. What could be observed by satellite is movement of shells or chemicals from one place to another.
From a recent CRS report, “It is not known from open sources which type of munitions Syria possesses. If unitary munitions are employed, it is not known whether chemical agent is stored in bulk, or warheads are filled in advance.” Recent news reports imply that Syria stores its chemical agents in precursor form, that is, two chemicals that react with each other to form the agent. The agents themselves are stable, but impurities lingering from the production process may make them unstable. More importantly, precursors are much less toxic than the agents themselves, which require only a pinhead amount on the skin to cause death. So handling the precursors is easier.
Binary shells were developed later, which remove some of the difficulties in handling unitary munitions. Binary munitions are loaded with precursors, which are mixed within the shells in flight.
We are not aware of programs in which the precursors are stored separately, then mixed and loaded into shells. It is possible that a country lacking the technology for mixing in flight might organize its program this way. The mixing and loading would have to be done by a mechanized line in a facility probably isolated from the atmosphere.
According to War of Nerves, the filling and storage of the United States’s Sarin chemical weapons took place in an airtight bunker like structure. [From the book]
Airtight, this building contained filling lines for the various type of munitions, including artillery shells, aerial bombs, and submunitions for cluster weapons. Each filling line had four or five stations enclosed inside sealed metal cabinets to prevent the escape of toxic fumes. At the first station, the machine loaded a projectile or bomb with a preset amount of liquid Sarin pumped from an underground storage tank. A conveyor belt carried the munition to the next station, where an overlay of helium gas was injected into the space remaining inside. The filling aperture was then capped, welded with a double seal, and vacuum tested for leaks using a helium detector. Because helium is an extremely small molecule that can penetrate the slightest leak, the presence of the inter gas in the air was an indicator of defective welds. Next the filled shells or bombs moved along the conveyor belt to another automated station that decontaminated the outside surfaces. Finally, the finished munitions were transported to an open packing area, where workers weighed, painted, stenciled, assembled, and crated them for storage.
Satellites could detect the movement of shells and precursor containers from storage to processing buildings, but, because mixing and filling would be done in a contained facility, satellites would not detect these operations. The artillery shells, while usually painted with markings indicating their content, would be hard to differentiate from satellite or drone photos. Or the reports about Syria mixing chemicals and filling shells and bombs could be based on pictures taken of the stockpiling of additional delivery vehicles at suspected Syrian chemical weapons sites.
During the filling process, the United States had numerous detectors (including rabbits and canaries) for leaks. Nevertheless, there were numerous incidents at American chemical weapons facilities and workers were exposed to the chemicals. In Syria, the only way for the US or other nations to detect mixing would be to detect the precursors or the agent itself in the atmosphere, which would require equipment on the ground or near the site. This might be done with drones equipped with specialized equipment, or with special forces. Israel claims that it has commandos inside Syria. If they are equipped with appropriate equipment, they could be the source of reports that mixing has started.
Satellite photography could show the movement of shells and containers at Syrian chemical munitions bases, but the evidence of mixing or filling shells is harder to obtain. It is also entirely possible that the source of the report was a coordinated leak designed to reinforce American/NATO red lines. In either case, satellite photos or airborne detection do not indicate intent. It is still premature to conclude that Assad is on the precipice of using his chemical weapons.