In an unusual move, Russia has sent the Organisation for the Prohibition of Chemical Weapons a detailed critique of its recent report on an alleged chemical attack in Syria.

In March, after a lengthy investigation, the OPCW’s Fact-Finding Mission (FFM) issued a report which found “reasonable grounds” for believing a toxic chemical had been used as a weapon in Douma and suggested the chemical was delivered by two gas cylinders dropped from the air.

Russia responded to this with a nine-page document which disputes the FFM's findings. It sent its critique to the OPCW on 26 April with a request to include it "as an official-series document of the Ninetieth Session of the OPCW Executive Council".

The OPCW appears to have spent a month deliberating about it, as it has only now been posted on the organisation's website.

The Russian document disputes (among other things) that the cylinders were dropped from the air. How they got there is a crucial question. If they were dropped from the air the obvious implication is the Assad regime was responsible, since rebel fighters in Syria had no aircraft.

On this point the Russian document echoes the findings of a OPCW employee, Ian Henderson, who produced an "engineering assessment" suggesting the cylinders had been "manually placed" in the spot where they were found (see previous blog posts here, here and here).

Henderson's findings were not mentioned in the FFM's report published in March, though the OPCW says they will be considered by its new Investigation and Identification Team (IIT) as part of any forthcoming work on Douma.

The brief of the IIT is to identify “the perpetrators of the use of chemical weapons” in Syria and to report on “all information potentially relevant to the origin of those chemical weapons”.

Henderson's assessment was an internal report, not intended for publication. However, someone leaked it and it was posted on the internet earlier this month.

On social media, defenders of the Assad regime treated the leaked document as automatic proof that the FFM’s report was wrong, and the Working Group on Syria, Propaganda and Media — which published the leaked document — presented it as evidence of a western plot to suppress the truth. The OPCW, it said, “has been hijacked at the top by France, UK and the US”.

The arguments about the cylinders in Henderson's document and in the Russian document are remarkably similar – suggesting, perhaps, that Russia was aware of Henderson's findings before they surfaced on the internet.

In its conclusions, the Russian document says: 

"The parameters, characteristics and exterior of the cylinders, as well as the data obtained from the locations of those incidents, are not consistent with the argument that they were dropped from an aircraft."

Henderson's document says:

"At this stage the FFM engineering sub-team cannot be certain that the cylinders at either location arrlved there as a result of being dropped from an aircraft. The dimensions, characteristics and appearance of the cylinders and the surrounding scene of the incidents, were inconsistent with what would have been expected in the case of either cylinder having been delivered from an aircraft."

The Russian document continues:

"The existing facts more likely indicate that there is a high probability that both cylinders were placed at Locations 2 and 4 manually rather than dropped from an aircraft."

Henderson's document continues:

"Observations at the scene of the two locations, together with subsequent analysis, suggest that there is a higher probability that both cylinders were manually placed at those two locations rather than being delivered from aircraft."

The Russian document discusses other issues relating to the FFM's report, but here is the relevant section on the cylinders:

Computer simulation of falling chlorine cylinders

A significant part of the FFM report supports the conclusion that the post-impact position of the cylinders in the apartment blocks matches the damage observed. However, no specific calculation is provided, and no information is given on the names of experts involved, nor on their competence or authority. It should be noted that the experts that developed the simulation and estimated the impact of the cylinder on the building structures did not indicate in the Report what drop height was used for their estimation — which is of critical importance.

(a) Based on charts and diagrams in the Report (Figure 10 on page 18, Figure A.6.6 on page 56, and Figure A.6.7 (b) on page 57), the calculation was made for the cylinder impacting the barrier at a speed of 30 to 60 m/s, which relates to a drop height of 45 to 180 metres. Figure 12 (page 19) displays the graphs for the residual velocity of cylinders falling from 150 metres.

In contrast, Syrian Air Force helicopters do not fly at altitudes of less than 2000  metres when cruising over towns, for security reasons. A helicopter flying at 200 metres over an active combat zone will come under fire from small arms at the least, and will be inevitably shot down.

If a cylinder had been dropped from that altitude, it would have developed a vertical speed of about 200 rn/s at the point of impact, and would have definitely not only destroyed the 20 cm thick roof, but would have caused more serious damage and would have been significantly damaged itself.

(b) In the opinion of Russian experts with regard to the calculations conducted by the FFM, we observe in reality the picture described below.

The shape and dimensions of the resulting aperture at Location 2 are more consistent with the penetration of a solid body through the reinforced concrete barrier at an angle of 80 to 90 degrees to the surface. The same is applied to the deformation of the barrier rebar.

The state of the observed cylinder is not consistent with the deformation that a cylinder filled with liquid chlorine could undergo under the above-mentioned conditions of penetration. In such a situation the front end of the cylinder should have been subject to a much more considerable deformation.

When impacting the rooftop, the cylinder was to alter its trajectory and its angle of approach to the barrier, which was not the case judging by the description of the crater in the roof.

The detailed study of the crater in the reinforced concrete barrier (the roof of the building), as well as the presence of smoke-black traces and the destruction of the barrier rebar inside the aperture, are more consistent with an explosion of a 120 mm mortar or an artillery projectile of the same calibre that approached the barrier along the arching trajectory.

This is also evidenced by the traces left by blast fragmentations on the walls of the balcony. The probability of the crater being formed by a mortar/artillery projectile or a similar munition is also supported by the presence of multiple apertures that are very much alike in the concrete plates on the rooftops of surrounding buildings (Figure A.6.3., page 55).

(c) The relative dimensions of the crater at Location 4 are not consistent with the relative dimensions of the cylinder found on the bed inside the apartment. The lateral dimensions of the crater supersede the diameter of the cylinder more than twofold, making them contradictory to the estimate and factual results of the piercing effect of solid bodies to the reinforced concrete barrier.

The presence of sticking out rebar elements consisting of soft and loose wires inside the crater is more likely indicative of a crater being widened mechanically from the outside rather than with a crater resulting from a solid body penetration.

The state of the observed cylinder is not consistent with the deformation that a cylinder filled with a liquid (chlorine) could undergo in case of flat penetration. Otherwise a cylinder should have been more flat in its shape, and the stabilizer fins, front-end valve and other add-on devices should have been subject to a considerable deformation, or absent altogether.

The conditions under Which the cylinder pierced through the roof terrace into the apartment did not allow for its shifting away from the piercing trajectory without causing collateral damage to furniture, the floor, walls, or window glazing, the testimony of which was not observed.

In the case of dropping of a body similar in shape and with an advanced stabilization system from a height of 100 m or above from an aircraft, the observed angles of approach are from 45 to 60 degrees from the surface of a barrier. This fact does not allow us to suggest the possibility of the cylinder falling down flat-wise after being dropped from an aircraft.

Therefore, at locations where the cylinders have been detected, the damage to the roof of the building and to the rooms beneath, or the visible deformations of the bodies of cylinders and their final positions, cannot lend credence to a version of the use of chlorine-filled cylinders delivered by an aircraft.

Conclusion

The Russian Federation does not challenge the findings contained in the FFM report regarding the possible presence of molecular chlorine on the cylinders. However, the parameters, characteristics and exterior of the cylinders, as well as the data obtained from the locations of those incidents, are not consistent with the argument that they were dropped from an aircraft.

The existing facts more likely indicate that there is a high probability that both cylinders were placed at Locations 2 and 4 manually rather than dropped from an aircraft.

Apparently the factual material contained in the report does not allow us to draw a conclusion as to the use of a toxic chemical as a weapon.

On that basis, the Russian Federation insists on the version that there was false evidence and on the staged character of the incident in Douma.