OPCW Releases Third Report by Investigation and Identification Team

Reasonable grounds to identify Syrian Arab Air Forces as perpetrators of 2018 Douma chemical attack

27 January 2023

The Hague, Netherlands—27 January 2023—The OPCW Investigation and Identification Team (IIT)’s third report concludes that there are reasonable grounds to believe that the Syrian Arab Air Forces were the perpetrators of the chemical weapons attack on 7 April 2018 in Douma, Syrian Arab Republic.  

Based on the holistic assessment of the large volume and wide range of evidence gathered and analysed, and on the convergence of the outcomes of such corroborated multiple analyses, the IIT concluded that, on the evening of 7 April 2018, at least one helicopter of the Syrian “Tiger Forces” Elite Unit dropped two yellow cylinders containing toxic chlorine gas on two apartment buildings in a civilian-inhabited area in Douma, killing 43 named individuals and affecting dozens more.   

“The use of chemical weapons in Douma – and anywhere – is unacceptable and a breach of international law,” said OPCW Director-General Ambassador Fernando Arias. 

“The Chemical Weapons Convention was signed 30 years ago – it represents a legally binding commitment of 193 States Parties to ban chemical weapons completely. OPCW’s Technical Secretariat was given a mandate by the Conference of the States Parties in June 2018 to identify the perpetrators of chemical weapons use in Syria. This report delivers on that mandate.”  

The IIT assessed physical evidence collected and provided by OPCW experts, States Parties, and other entities. This includes 70 environmental and biomedical samples, 66 witness statements, and other verified data, such as forensic analysis, satellite images, gas dispersion modelling, and trajectory simulations. The evidence was scrutinised by IIT investigators, analysts, and several external independent experts.  

The IIT considered a range of possible scenarios and tested their validity against the evidence they gathered and analysed to reach their conclusion: that the Syrian Arab Air Forces are the perpetrators of this attack. 

The conclusion of the report is reached on the basis of “reasonable grounds”, which is the standard of proof consistently adopted by international fact-finding bodies and commissions of inquiry. The IIT conducted its investigation between January 2021 and December 2022.  

Director-General Arias added: “The world now knows the facts – it is up to the international community to take action, at the OPCW and beyond.” 

Read the full report


The mandate of the IIT is to identify the perpetrators of specific instances of chemical weapons use in the Syrian Arab Republic. It is responsible for investigating only those instances in which the Fact Finding Mission (FFM) has determined that use or likely use of chemical weapons in Syria has occurred, as well as cases for which the now expired OPCW-United Nations Joint Investigative Mechanism (JIM) did not issue a report.  

The IIT is tasked with fact-finding and is not a prosecutorial or judicial entity. It is not responsible to determine criminal responsibility of individuals, organisations or States. Furthermore, the IIT does not make recommendations for future action. These issues pertain to the policy-making organs of the OPCW (i.e. the Conference of States Parties, Executive Council) and other relevant bodies. According to the decision of the Conference of States Parties, the report is shared with the United Nations Secretary-General.  

As the implementing body for the Chemical Weapons Convention, the OPCW, with its 193 Member States, oversees the global endeavour to permanently eliminate chemical weapons. Since the Convention’s entry into force in 1997, it is the most successful disarmament treaty eliminating an entire class of weapons of mass destruction. 

Over 99% of all declared chemical weapon stockpiles have been destroyed under OPCW verification. For its extensive efforts in eliminating chemical weapons, the OPCW received the 2013 Nobel Peace Prize. 

More Information

Syria and the OPCW  

IIT fact sheet 

OPCW Fact-Finding Mission  

OPCW Issues Fact-Finding Mission Report on Chemical Weapons Use Allegation in Douma, Syria, in 2018 

Timeline: Syria and the OPCW 

What is a chemical weapon? 

What is a dual-use chemical?   

First IIT report 

Second IIT report