he document, whose authenticity the OPCW has confirmed, contends that the official story which was used to justify an air strike by the US, UK and France about poison gas being dropped on civilians from Syrian government helicopters is scientifically implausible, saying "In summary, 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 document, titled "Engineering Assessment of Two Cylinders Observed at the Douma Incident", was signed by a man named Ian Henderson, whose name is seen listed in expert leadership positions on OPCW documents from as far back as 1998 and as recently as 2018.