Firstly, sarin is difficult to make. Anyone who claims otherwise is oblivious to both history and chemical engineering. Germany, the US and the former Soviet Union took years to perfect the process. Its production requires a number of complex steps and the ability to handle highly dangerous chemicals at very closely controlled high temperatures and pressures. There is no evidence anyone has come up with any sort of streamlined method to manipulate the molecules to make sarin.
Second, quantity. Perfecting the process isn’t enough – there is a difference between making a spoonful and enough for the August attacks, which would have needed about half a ton. This assumes a scale only reached by big state production programmes. To put it in perspective, the one verified example of non-state production of sarin was the Aum Shinrikyo cult in Japan. Their many millions of dollars, very large purpose-built manufacturing facility and highly qualified staff got them the ability to make single batches of perhaps 8 litres of short shelf life Sarin. The alleged Aleppo plant wouldn’t need to be the size of the Rocky Mountain Arsenal in the US, but it would have needed to be closer to that than the size of a house.
Third is the choice of weapon. Of the panoply of chemical warfare agents available to modern science and engineering, sarin is one of the hardest to make. So why was this one chosen? Even its nerve agent kin, Tabun and VX, are arguably easier to produce; mustard or lewisite are easier and use less technology. Numerous toxic industrial chemicals which might “fly under the radar” of non-proliferation regimes could be used as weapons. So why pick the hardest?
Fourth, economics. To make this operation work it is going to take a lot of highly trained people, raw materials, and specialised equipment, as well as a facility. It would cost many tens of millions of dollars. When the rebel factions are so stretched for resources, does it make any sense to spend, say, $50m on a weapon of limited utility? Lavish expenditure must raise a paper trail somewhere; there would be order books and receipts. Let’s see them.
Fifth is logistics. You don’t turn precursor material magically into sarin: you need about 9kg to end up with 1kg of sarin. This stuff has to come from somewhere, but where? Hersh omits these details, as do most of the alternative narratives. It is simply assumed that things like phosphorus trichloride and thionyl chloride just get summoned up in vast quantities without someone noticing. Most commentators on this issue have also forgotten about something called conservation of mass. If you use 9kg of material to synthesize 1kg of sarin you end up with 8kg of waste, rather a lot of which is very dangerous, smelly and corrosive. This waste stream has to go somewhere, and someone will notice. There are also the logistics of getting a lot of sarin into rockets and getting those rockets from Aleppo to Damascus.
Sixth, concealment. How do you hide all of this? The building, the supply chain, the people, the money, and the very smelly waste stream. Where are they? They need to be concealed not just from the Syrian regime but from other rebel factions, western intelligence agencies, the Russians, and perhaps even your own people who might desert, get captured or say silly things on YouTube videos. There is deathly silence from Aleppo and we only find out about it from Hersh?
Lastly is the specificity of the product. There are important physical clues found in the traces of sarin at the impact sites of the 21 August rocket attack. One of these is the presence of hexamine, a chemical with no history of use in nerve agent production. But hexamine can be used as an acid scavenger, and thus its presence could be explained due to its use as an additive to the sarin. This idea has been reinforced by both the admission of the Syrian regime that they used hexamine as part of their formula, and by Syria’s declaration to the OPCW of an inventory of 80 tonnes of hexamine, specifically as part of their chemical weapons program. Surely, as an uncontrolled substance, they could have omitted it from their declarations. But they didn’t. Hexamine in field samples plus hexamine in Syrian inventories, plus an admission that hexamine was in their recipe, seems a compelling case for tying the Sarin in the field to the Syrian regime. How would an Aleppo-based rebel factory somehow come up with the same exact idea?
Taken cumulatively, all these points add up to a very high degree of improbability. Isn’t it more probable that the Sarin came from the people who confessed to having a Sarin factory, fired from areas controlled by the government 2km away from the impact sites, in munitions the government had been using since 2012?