The global chemical weapons watchdog on Friday blamed Syrian President Bashar Al Assad's regime for a 2018 chlorine gas attack near Damascus that killed 43 people.
Investigators said there were “reasonable grounds to believe” that at least one Syrian air force helicopter had dropped two cylinders of the toxic gas on the rebel-held town of Douma during the civil war.
Damascus and its ally Moscow claimed the attack was staged by rescue workers at the behest of the US, which launched air strikes on Syria days afterwards, along with Britain and France.
But the Hague-based Organisation for the Prohibition of Chemical Weapons said its investigators had “considered a range of possible scenarios” and concluded that “the Syrian Arab Air Forces are the perpetrators of this attack”.
“The use of chemical weapons in Douma — and anywhere — is unacceptable and a breach of international law,” OPCW Director-General Fernando Arias said in a statement.
“The world now knows the facts — it is up to the international community to take action, at the OPCW and beyond.”
In one of the first responses to the report, Britain said it shared the OPCW's assessment and commended its “resilience, professionalism and expert independent analysis in the face of desperate attempts by Syria and Russia to block this investigation”.
“We remember the victims of the Douma attack and remain committed to pursuing the justice they deserve,” Tariq Ahmad, UK Minister of State for the Middle East, said in a statement. “We are steadfast in our commitment to holding all those who use chemical weapons to account.”
The OPCW said that “at least one Mi-8/17 helicopter of the Syrian Arab Air Force, departing from Dumayr airbase and operating under the control of the Tiger Forces, dropped two yellow cylinders” on April 7, 2018.
The cylinders hit two residential buildings in central Douma, it said.
The first “ruptured and rapidly released toxic gas, chlorine, in very high concentrations, which rapidly dispersed within the building, killing 43 named individuals and affecting dozens more”.
The second cylinder smashed into an apartment and slowly released some chlorine, “mildly affecting those who first arrived at the scene”.
Investigators examined 70 environmental and biomedical samples, 66 witness statements and other data including forensic analysis, satellite images, gas dispersion modelling and trajectory simulations.
Douma was the final target of the government’s sweeping campaign to take back control of the eastern Ghouta suburbs of Damascus from rebels after seven years of revolt. Rebel fighters gave up the town days after the chlorine attack.
Emergency workers said at the time that they had treated people suffering breathing problems, foaming at the mouth and other symptoms.
OPCW inspectors visited the scene after delays and determined that chlorine was used, however they did not have the remit at the time to say who they believed was behind the attack.
But thanks to new rules, which Syria and Russia have opposed, the watchdog is now able to point the finger of blame.
Syria has accused rebels and emergency workers of staging the attack by bringing in dead bodies and filming them, or alternatively arguing that a rebel chemical weapons factory was hit.
But the OPCW said its team “thoroughly pursued lines of inquiry and scenarios suggested by Syrian authorities and other state parties, but was unable to obtain any concrete information supporting them”.
It also said it “regrets” that Syria refused to allow it further access to the site to investigate.
The report also dismisses claims by former inspectors who alleged that the watchdog had altered original findings in 2018 to make the evidence of a chemical attack seem more conclusive.
It added that the basis of “reasonable grounds” was the “standard of proof consistently adopted by international fact-finding bodies and commissions of inquiry”.
Damascus denies the use of chemical weapons and insists it has handed over its stockpiles under a 2013 agreement, prompted by a suspected sarin gas attack that killed 1,400 in Ghouta.
The OPCW’s Investigation and Identification Team effectively replaced an earlier investigative mechanism set up between the UN and OPCW in 2015, which was disbanded two years later after Russia vetoed an extension of its mandate at the Security Council.
In an attempt to ensure accountability for crimes in Syria, the UN has established an “international, impartial and independent mechanism”, mandating it to preserve and analyse evidence of crimes and prepare files for trials in “national, regional or international courts or tribunals that have or may in the future have jurisdiction over these crimes, in accordance with international law”.
The ongoing Syrian conflict began more than a decade ago and has killed hundreds of thousands and displaced half the country’s prewar population of 23 million.
With reporting from agencies