Re: Leaked OPCW report suggests Syria gas attack was ‘staged,’ MIT scientist says

Ted Postel comments:

As you know, when the OPCW document indicating staging of the chlorine cylinder attacks in the alleged attacks in Douma on April 7, 2018 were released, I was traveling and in Washington with little time to look more deeply into the matter.  I have been crashing on this problem during the last few days and I have comprehensively reviewed the observed data and calculations reported in S/1731/2019.  The attached PDF file contains my findings in detail.

My review of the conclusions in the UN OPCW Fact-Finding Mission Report (FFM) S/1731/2019 shows that the science-based analysis used in the report and the observed data collected by the FFM all contradict each other.

The presumed inputs to the science-based finite element calculations also appear to have been carefully chosen in an attempt to get results where the cylinder did not penetrate through a steel reinforced concrete roof – which if true, could have indicated that staging of the event was improbable.  The input that was chosen required a helicopter drop-height that would have been extremely vulnerable to ground fire from assault rifles (particularly from AK-47 assault rifles). 

Even then, the results of the cylinder impact calculations were inconsistent with the observed characteristics of the crater and hole on the roof at the alleged attack-site.  Observations of the attack site were inconsistent with the results of the “tuned” calculations.  Unlike what was predicted by the calculations, rebar in the concrete was observed to have failed catastrophically as it was blown (by the detonation of an artillery rocket or mortar at the surface of the roof) to an angle of more than 60° relative to the incoming direction of the cylinder.  The tuned calculations also predicted that the impact hole would have a diameter closely matching that of the allegedly dropped cylinder.  Instead the hole had a diameter nearly twice that of the cylinder.  All scholarly publications on objects penetrating concrete slabs show that the diameter of holes produced by impacts should be nearly the same as the diameters of the projectiles.  This is a result of the brittle characteristics of concrete, even when reinforced with rebar.

The tuned calculation with the artificially chosen inputs instead showed that the rebar should have been intact, as the plastic deformation of the rebar was the only mechanism that could have led to the misleading prediction that the cylinder would come to a stop without penetrating the roof.  Thus, the results of the tuned science-based calculations were incompatible with the observed facts at the site of the crater and hole.  The conclusions reported by the OPCW to the UN Security Council were therefore incompatible with both the findings of the tuned calculations and the observations from the site.

In addition, the assumed impact speed of the chlorine cylinder used in the tuned calculations required that cylinder be dropped from a helicopter at an altitude of between 50 and 250 m, with the most likely altitudes being between 50 and 130 m.  At these altitudes helicopters would be highly vulnerable to ground fire from AK-47 assault rifles, or even hand guns – which are ubiquitous in these environments.  Evidence from earlier studies of Syria’s barrel bombing campaigns performed by my colleague Richard Lloyd indicate that the altitude used by Syrian helicopters is often close to about 2 km or higher.  This choice of an operational altitude is consistent with procedures aimed at operating above altitudes where damage can occur from anti-aircraft fire from AK-47 assault rifles.

A crater and hole in a building adjacent to the inspected site had exactly the same ratio of hole to spallation damage diameters as that of the inspected crater.  For some inexplicable reason, no attempt was made by the OPCW to establish or report the absolute dimensions of the crater.  I estimate the absolute dimensions of the crater to be very close to that at the inspected site from the apparent depth of the spallation crater and the assumption that the thickness of the adjacent concrete roof is about the same as the roof at the inspected site.  This could indicate that holes and craters on both roofs were produced by the same type of munition detonating at the same angle relative to vertical (and therefore fired from the same range and azimuth).

I believe that the leaked report that indicates the attack sites were staged is an indication of high professional integrity and competence within the OPCW working staff.  In contrast, I conclude that the UN OPCW report S/1731/2019 is a product of compromised reporting of the inspection and analysis process by upper level OPCW management.