Chemical Challenges in Syria

Ralf Trapp, Richard Guthrie, Jean Pascal Zanders and Alastair Hay

(18-minute read)

On 7 April 2018, Syrian forces hit Douma, a town in the Eastern Ghouta region east of Damascus, with a toxic chemical agent presumed to be chlorine. More than 40 people are believed to have been killed, while scores more were exposed to the agent’s deleterious effects. It is the third major chemical strike recorded in 2018. The incident exemplifies the challenges the international community in general, and the Organisation for the Prohibition of Chemical Weapons (OPCW) in particular, face. As events over the past year demonstrate, the world can unite in the condemnation of chemical warfare, but the attribution of responsibility for violation of international laws of war and the norm against the use of poison remains politically sensitive and subject to immediate geopolitical interests. The international split and resulting paralysis in organisations responsible for international peace and security and the prevention of chemical warfare enable the continuation of chemical attacks.

Besides investigating alleged use of chemical weapons (CW), OPCW operations in Syria have also included the elimination of the country’s chemical warfare capabilities after accession to the Chemical Weapons Convention (CWC) in October 2013. These operations posed a particular challenge, as no CW destruction and onsite verification activities had ever been conducted in active war zones. The states parties to the CWC adapted operational procedures maintained by the Technical Secretariat of the OPCW. The Technical Secretariat had also already concluded memoranda of understanding with other international organisations, including the United Nations, in anticipation of eventualities such as those presented in Syria. They laid the foundation for collaboration in the field. The successful evacuation of chemical agents and their precursors undoubtedly prevented escalation of chemical warfare in the Syrian civil war, as is paradoxically testified by the resort to chlorine as an agent of choice. Indeed, despite 100 years of scientific and technological progress, the agent used in the first major chemical attack near Ypres, Belgium in April 1915, made its tragic comeback to the battlefield.

Also in 2013, the OPCW received the Nobel Peace Prize for its work in eliminating CW stockpiles worldwide and its contribution to the prevention of the re-emergence of CW. It thrust an anonymous organisation into the spotlight. Today, events in Syria overshadow the OPCW’s successes: its membership is only second to that of the United Nations; it had verified the destruction of over 90,000 metric tonnes of chemical agents and associated delivery systems and infrastructure. It has also conducted special operations not just in Syria, but also in Libya. Today, public impressions could easily nurture a discourse of failure of the disarmament enterprise.

For this edition of Trust & Verify, VERTIC has invited four experts in CW disarmament to share their impressions of the achievements of the OPCW and the challenges the CWC currently faces with respect to the war in Syria. The authors – Ralf Trapp, Richard Guthrie, Jean Pascal Zanders and Alastair Hay – each address specific facets: weapon elimination, investigation of alleged use, the difficulties with attribution, and the outrage by industry and scientific associations about the misuse of chemistry. Yet their contributions find great commonality about the challenges the Syrian case poses to the norm against CW.

Ralf Trapp: On the disarmament of Syria’s chemical weapons

In 2012, when the Technical Secretariat of the OPCW first looked into the challenges it might face if called to ‘go into Syria,’ it could hardly imagine that it would be deployed into an active war zone to remove hundreds of tonnes of CW, and to destroy the associated manufacturing infrastructure.

This changed after the United Nations Secretary-General confirmed the sarin attack on Ghouta in August 2013. To prevent punitive Western air strikes, Russia and the United States agreed on a framework for the elimination of Syrian CW. Synchronised with Syria’s accession to the CWC on 14 September 2013, the OPCW Executive Council transferred this framework into a series of decisions that set out the order of destruction and the verification procedures for eliminating Syria’s CW stockpile and its mobile and stationary production facilities.  The Security Council sanctioned these decisions and established the UN-OPCW Joint Mission to supervise their implementation.

Within days, the OPCW deployed the first team of inspectors and verification experts to Damascus to make arrangements for the future removal and inspection work and to provide technical guidance to the Syrian authorities on the requirements for their disclosure of CW materials, equipment and facilities. This first mission was followed by regular team deployments supported by offices working out of Damascus and at times Latakia, as well as Beirut and Nicosia. While the footprint of these deployments was kept to a minimum, OPCW inspectors were able, within the extremely short timelines established, to verify the Syrian declaration and secure the declared facilities and materials. The teams were also able to render the declared production and mixing equipment unusable, supervise the in-country destruction of materials (isopropanol, mustard agent contaminations), and supervise the preparation and repackaging as necessary of the remaining chemicals for removal from Syria.

Beginning in January 2014, the Joint Mission supervised the transportation of 1,300 tonnes of declared chemical agents and key precursors across the conflict zone to the port of Latakia. There, chemicals were loaded onto two container ships (made available by Norway and Denmark) and transported to Germany, Finland, the United Kingdom, and the United States for disposal. Several hundred tonnes of the most dangerous chemicals—methylphosphonyl difluoride (DF), a sarin binary component, and mustard agent—were shipped to Italy for reloading onto US vessel Cape Ray, which had been fitted out as a destruction facility and completed their destruction at high sea by August 2014.  The effluents of this operation were subsequently destroyed in Germany.

The elimination of Syria’s CW production facilities—both mobile and stationary, including some set up in tunnels and aircraft hangars—took place alongside these removal operations, albeit hampered by access limitations to some facilities given security constraints. The last two of these facilities were inspected by the OPCW in November 2017, and work towards their final destruction was underway in early 2018.

The Joint Mission closed down on 30 September 2014. The OPCW continued inspections to complete the elimination of the remaining CW production facilities, supported by the United Nations Office for Project Services (UNOPS). Its widely recognised success was made possible by the close collaborations of the OPCW and the UN in Syria and between their respective headquarters—both contributing their specific competencies and capacities in a complex undertaking in unchartered political, legal, security and technical territory. It also was possible thanks to financial and in-kind contributions by a large and diverse number of countries. However, it did not altogether stop the use of CW in the Syrian conflict, and neither did it resolve all the questions about the accuracy and completeness of the Syrian declaration.

New CW uses were reported beginning in spring 2014, leading to the establishment of the OPCW Fact-Finding Mission (FFM) and subsequently the UN-OPCW Joint Investigative Mechanism (JIM).

Moreover, concerns about gaps in the Syrian declaration led to the establishment of the Declaration Assistance Team (DAT) in April 2014. The DAT, set up initially by the Director-General in consultation with Syria and subsequently endorsed by the Executive Council, attempted to reconstruct the genesis of the Syrian CW programme. It assessed the data available from the Syrian declaration and subsequent submissions, from previous inspections, as well as information made available by states parties. The DAT deployed to Syria on numerous occasions to interview senior personnel involved in the Syrian CW programme, visit sites of particular interest, including Syria’s Scientific Studies and Research Centre (SSRC), and collect and analyse samples as physical evidence of agents and activities that Syria still needed to disclose. Its work resulted in the declaration by Syria of facilities and activities, including work with ricin. Its latest round of inspections of the SSRC facilities in Barzah and Jamarayah was conducted in November 2017, and samples then collected were sent to Designated Laboratories of the OPCW for analysis in February 2018.

Richard Guthrie: On investigating alleged use of CW in Syria

In March 2013, when the first formal allegations were made regarding the use of chemical weapons in Syria, the country was not a party to the CWC. This precluded using the measures agreed within the text of the Convention for investigation of alleged use as they only apply to states parties. However, there was another arrangement that could be used that was overseen by the UN Secretary-General (UNSG). This arrangement, known as the UNSG mechanism, was used to establish an investigation led by Åke Sellström. The Sellström team had been in Syria for only a few days when on 21 August 2013 the sarin attack in East Ghouta took place. The team was tasked to investigate the incident as a priority.

The Sellström team took environmental samples (including from munitions), biomedical samples from people who indicated they had been exposed to the poison and interviewed witnesses. Its report concluded that the nerve agent sarin had been used but did not formally attribute blame for who used it.  Many Western governments assessed that Syrian forces had carried out the attack. The Syrian and Russian governments denied this.

While the final Sellström report was in preparation, Syria joined the CWC. Once Syria was a State Party to the Convention, it was no longer appropriate to use the UNSG mechanism. However, the provisions of the Convention were not ideally suited for what was going to be ongoing investigations into alleged use. The FFM (mentioned by Ralf Trapp above) was established as an ad hoc arrangement ‘based on the general authority of the OPCW Director-General to seek to uphold at all times the object and purpose of the Chemical Weapons Convention’. The FFM was used by the OPCW to carry out investigations in circumstances that had not been discussed in the negotiations that concluded the text of the CWC.

On its first outing, in May 2014, the FFM convoy came under attack, and a vehicle was damaged beyond repair. While there were no serious injuries sustained by the FFM personnel, understandable concerns about the safety of investigators put limitations on investigation activities.

Despite these limitations, the FFM concluded in June 2014 that toxic chemicals, most likely a pulmonary irritating agent such as chlorine, had been used in the Syria conflict. In its second report, published in September 2014, the FFM resolved that it had found information constituting ‘compelling confirmation’ that a toxic chemical had been used ‘systematically and repeatedly’ as a weapon in villages in northern Syria earlier in the year. It noted ‘the descriptions, physical properties, behaviour of the gas, and signs and symptoms resulting from exposure, as well as the response of patients to the treatment’. The FFM, therefore, determined ‘with a high degree of confidence that chlorine, either pure or in mixture, is the toxic chemical in question’.

These conclusions of the FFM were challenged, most notably by Russia, on grounds such as that interviews with witnesses had been carried out away from the scenes.

The FFM was not given the mandate to attribute who carried out the attacks, but it did find clear evidence of use. To allow for attribution, the UN-OPCW JIM was established by United Nations Security Council resolution 2235 (adopted unanimously on 7 August 2015). The JIM produced seven reports.  JIM operations were overseen by a ‘Leadership Panel’ of Virginia Gamba, Adrian Neritani and Eberhard Schanze. The appointment of a Leadership Panel was intended to reduce the potential for political pressure on the investigation by creating independence from governments in its leadership. The political issues surrounding attribution are considered by Jean Pascal Zanders below.

The third and fourth JIM reports determined that the Syrian armed forces have been involved in the use of toxic chemicals as weapons in three cases: Talmenes, on 21 April 2014; Qmenas, on 16 March 2015; and Sarmin, on 16 March 2015. The third report also concluded that the so-called Islamic State (also called ISIL, ISIS or Daesh) had been involved in the use of mustard gas in Marea, on 21 August 2015.

The JIM mandate was renewed for a year by the adoption of United Nations Security Council (UNSC) resolution 2319 on 17 November 2016. A new Leadership Panel was appointed:  Edmond Mulet, Judy Cheng-Hopkins and Stefan Mogl.

Under the new Leadership Panel, the JIM reviewed two new cases identified by the FFM concerning incidents reported in Umm Hawsh, Aleppo Governorate, in September 2016, and Khan Shaykhun, Idlib Governorate, on 4 April 2017. On the Khan Shaykhun attack, the FFM had reported: ‘Based on its work, the FFM is able to conclude that a large number of people, some of whom died, were exposed to sarin or a sarin-like substance. The release that caused this exposure was most likely initiated at the site where there is now a crater in the road. It is the conclusion of the FFM that such a release can only be determined as the use of sarin, as a chemical weapon.’  Drawing on this, and other evidence, the seventh JIM report stated, ‘the Leadership Panel is confident that the Syrian Arab Republic is responsible for the release of sarin at Khan Shaykhun on 4 April 2017.’ Russia rejected these findings and suggested that the JIM conclusions were based ‘primarily on assumptions and a selective use of facts’.

The lack of consensus on the JIM findings remains. When the JIM mandate came up for renewal again towards the end of 2017, Russia cast its veto within the Security Council. Eleven of the fifteen members of the Council voted in favour.

At present, there are two ongoing investigation arrangements—the Independent International Commission of Inquiry on the Syrian Arab Republic, which is a broad range of activities within the Syria conflict, and the International, Impartial, and Independent Mechanism for Syria (IIIM) in December 2016, established by UN General Assembly resolution 71/248. Neither has the resource or expertise that was embodied in the JIM.

On 8 April 2018 further allegations of use of CW were made. Numerous reports suggested the use of CW in the town of Douma in Eastern Ghouta. These latest allegations highlight the need for investigatory capacities.

Jean Pascal Zanders: On the challenge of attributing responsibility

After Syria’s accession to the CWC in October 2013, the international community almost immediately had to confront a vexing dilemma: how to ensure the country’s full cooperation with the international efforts to eliminate its chemical warfare capabilities while seeking criminal justice for the use of CW in the civil war. A silent understanding not to further investigate responsibility for the sarin nerve agent strikes against Ghouta on 21 August 2013 accompanied the Syrian government’s agreement to forego CW. After a lull of seven months, the first reports of chlorine strikes against territories under insurgent control emerged in April 2014. The rapid increase in the number of incidents, details about the nature of the attacks, and casualty reports led the Director-General of the OPCW, Ahmet Üzümcü, to establish the FFM within the Technical Secretariat.

The CWC, however, does not give the Technical Secretariat the mandate to determine responsibility for the attacks. To this end, the UN Security Council unanimously adopted Resolution 2235 on 7 August 2015 establishing the UN-OPCW JIM. The OPCW limited its role to supplying factual information in support of the JIM’s mission. In November 2017, Russia refused to renew its mandate. In response, France launched on 23 January 2018 the International Partnership against Impunity for the Use of Chemical Weapons. At the time of writing, 25 countries and the European Union had signed up to the Declaration of Principles.  They have thereby committed themselves, among other things, to gather information on those who are responsible for chemical warfare with a view of holding them accountable in the future. They also pledge to collaborate to bring such persons and entities to justice.

Two other UN initiatives collect information on war crimes to support future trials. In August 2011, the Human Rights Council set up the Independent International Commission of Inquiry on the Syrian Arab Republic (COI). Several reports, which draw on interviews, analysis of documentary evidence, medical and forensic investigations, and other sources, refer to CW use. The COI frames the allegations in a human rights context.

Taking note of the blockage in the Security Council, the UN General Assembly established the International, Impartial, and Independent Mechanism for Syria (IIIM) in December 2016. According to Resolution 71/248, IIIM is ‘to collect, consolidate, preserve and analyse evidence of violations of international humanitarian law and human rights violations and abuses and to prepare files in order to facilitate and expedite fair and independent criminal proceedings, in accordance with international law standards, in national, regional or international courts or tribunals’. Its mandate also stipulates cooperation with the COI.

The difficulty of attribution

One can easily quip that in any investigation into allegations of CW use, however controlled the process and assiduous the analyses, the truth is never scientific; it is always political. Attribution is not an end in its own right; it is a step towards achieving justice. That finality, however, appears illusive. Historically, no single individual has ever been indicted and convicted under international criminal law for violating rules or the norm against chemical warfare. Calls for justice fluctuate between the legalist position that without punitive justice there can be no peace or reconciliation, on the one hand, and a more pragmatist approach that justice may be pursued at a later stage of the transitional process, on the other hand. States’ interest in justice may shift quite fast depending on factors such as war developments, domestic contingencies, or the forum in which national positions are being expressed.

Regarding Syria’s civil war, three elements appear particularly salient to the attribution question. First, no clarity exists about what attribution beyond the immediate gratification of naming and shaming can ultimately achieve. On 22 May 2014 China and Russia vetoed a draft UN Security Council Resolution to refer Syria to the International Criminal Court, thereby foreclosing that particular route for justice. Upon her resignation from the COI in August 2017, Carla del Ponte called for a special tribunal to circumvent vetoes in the Security Council. Her appeal gained little traction.

Second, there has been little clarification of the juridical purpose of attribution. For instance, the JIM mandate did not specify whether its reports represent evidence as being ‘beyond reasonable doubt’, ‘more likely than not’, ‘plausible’, or ‘reliable as to its truthfulness and usefulness’, conditions which have different legal weight in trial contexts. Without such clarification, in the political sphere, the findings may be used as justification to take action, including sanctions. Unilateral resort to retribution may easily delegitimise the whole attribution process.

Finally, the OPCW works towards fully eliminating Syria’s CW capabilities. Disarmament requires cooperation with government authorities, irrespective of the nature of the government in question. Given the unique situation of disarmament under war conditions in Syria, cooperation includes the government guaranteeing the safety and security of OPCW staff during onsite activities. Yet, calls for regime change often accompany calls for justice. This raises the question why the regime would want to collaborate when knowing that this will not ameliorate longer-term regime security. Given that a similar situation presented itself during the disarmament of Iraq in the 1990s, this conundrum requires future consideration.

Alistair Hay: The role of stakeholder communities

As noted by my colleagues, the OPCW established the FFM to investigate allegations of the use of chemical weapons in Syria. In the second of the FFM’s reports, it confirmed that chlorine had indeed been used as a weapon in Syria, in several locations.  The confirmation was based on evidence collected which included personal testimony from witnesses, medical professionals and others; screen grabs of photographic evidence of vegetation showing leaves of plants dried, shrivelled and turning yellow; medical records; details about people and animals who had died; descriptions of the agent being pungent, irritating and like ‘chlorine’; together with the sound bombs made when dropped which were described as more of a ‘thud’ than the ‘boom’ of conventional ordnance. Further evidence included a 1 x 2-metre barrel reported to contain chlorine, a bomb with a ‘CL2’ marking, the symbol for chlorine; and descriptions of the cloud released which appeared honey-wax to yellow in colour.

The JIM was established with the remit to both investigate and hold accountable those responsible for using chlorine as a weapon.  In the third of its reports, the JIM reported that the evidence it had reviewed enabled it to conclude that the Syrian Arab Republic was responsible for dropping chlorine barrel bombs in three locations namely Talmenes (21 April 2014), Sarmin (16 March 2015) and Marea (21 August 2015).

Reaction to this news from the academic chemistry community was swift, with numerous resolutions passed by societies condemning the use of chlorine as a weapon.  One of the first to do this was EuCheMS, the European Association for Chemical and Molecular Sciences representing more than 160,000 chemists from more than 40 Member Societies and other chemistry-related organisations.  At the 6th EuCheMS Chemistry Congress in Seville, 36 Presidents of Chemical Societies in Europe and beyond, or their representatives, signed a declaration deploring the use of CW in Syria and calling for the misusers of chlorine to be brought to justice. Others, including the International Union of Pure and Applied Chemistry (IUPAC) and more than 40 international and national scientific chemical societies from Africa, Europe, the Middle East, and North America issued similar statements.

However, it was not just the academic chemistry community who felt betrayed by the use, as a weapon, of a chemical with so many beneficial uses. The chemical industry was equally strident in its condemnation of chlorine as a chemical weapon. Those condemning use included the European Chemical Industry Council, Cefic,  representing 29,000 large, medium, and small chemical companies in Europe, the American Chemical Council,  and the International Council of Chemical Associations, with a membership producing some 90% of the world’s supply of chemicals. All three organisations called for chemicals not to be used deliberately to harm.

However, chlorine is but one of the CW used in Syria. The much more lethal sarin has been used on a least two occasions, the first in the attack on Ghouta, east of Damascus, on 21 August 2013 and the second on Khan Shaykhun on 4 April 2017.  Both attacks were investigated by OPCW experts, who before Syria’s accession to the CWC assisted the UNSG’s investigation. With investigators already in Syria at the time of the Ghouta attack, negotiations with the Syrian government and opposition forces proceeded rapidly to enable the expert teams to deploy for an onsite collection of evidence. Detailed interviews with survivors and treating clinicians, environmental sampling at the attack site together with extensive biomedical sampling provided clear and unequivocal evidence that sarin had been used in an attack which is estimated to have killed well over 1000 people. The report on the Ghouta attack describes what was found, without attributing blame. It was left to others, like the non-governmental organisation Human Rights Watch to review the evidence and conclude that the Syrian government was the perpetrator.

Circumstances were different when Khan Shaykhun was attacked. With Syria now a party to the CWC, the OPCW conducted its own investigation. Attribution could now be determined by the JIM. The JIM considered evidence from many sources including that from the FFM where witnesses had been interviewed, and of the blood samples collected seven had sarin, or sarin-like agents present.  Urine from three of these victims contained the metabolite specific to sarin, isopropyl methylphosphonate (IMPA) and analysis of autopsy samples from three victims confirmed the presence of sarin, or sarin-like substances in blood, brain, liver, lung and hair. Sarin and its degradation products were also found on vegetation, a rock and in dead birds.

On this occasion, the JIM’s task was made easier because the OPCW had taken samples of precursor chemicals from Syrian stockpiles before their destruction in 2014. Five of these samples were of the sarin precursor methylphosphonyl difluoride (DF), and the JIM had these analysed for impurities.

Analysis of environmental samples collected at Khan Shaykhun confirmed that sarin was produced by the binary route, in which DF is combined with isopropanol in the presence of hexamine. The presence of impurities in these samples also matched those present in the former Syrian DF stockpiles including phosphorus hexafluoride, isopropyl phosphates and isopropyl phosphorofluoridates (the latter two produced when DF from the Syrian stockpile which contained the impurity phosphorous oxychloride was used in a binary process to make sarin). This (and much other evidence) led the JIM to conclude that the Syrian government was responsible for dropping a large bomb containing around 150 -250 litres of sarin, which resulted in the death of 100 people and 200 other casualties.


Dr Jean Pascal Zanders is a disarmament researcher/consultant and heads The Trench, a research initiative dedicated to the future of disarmament (and chemical/biological weapons in particular).


Ralf Trapp is an independent consultant on chemical and biological weapons arms control and security, previously with the OPCW.


Richard Guthrie runs CBW Events, a project to create a record of events to enable and encourage understanding of how policies on the issues relating to chemical and biological warfare (CBW) and its prevention are developed.


Alastair Hay, Professor (Emeritus) of Environmental Toxicology at the University of Leeds, UK, has worked on chemical weapons issues for many years including conducting six investigations of allegations of their use.

Sources and further reading Executive Council documents EC-M-33/Dec.1 of 27 September 2013; EC-M-34/Dec.1 of 15 November 2013; EC-M-34/DG.1 of 25 October 2013; EC-M-44/DG.2 of 25 August 2014; EC-81/Dec.4 of 23 March 2016, EC-83/Dec.5 of 11 November 2016, EC-87/DG.16 of 23 February 2018. JIM reports (UN Documents S/2016/142, S/2016/530, S/2017/567, S/2016/738/Rev.1, S/2016/888, S/2017/131, S/2017/552 and S/2017/904).

Organization for the Prohibition of Chemical Weapons, Director-General, ‘Summary Report of the Work of the OPCW Fact-Finding Mission in Syria Covering the Period from 3 to 31 May 2014’, S/1191/2014, 16 June 2014.

Organization for the Prohibition of Chemical Weapons, Director-General, ‘Second report of the OPCW Fact Finding Mission in Syria’, S/1212/2014, 10 September 2014.

Note by the Technical Secretariat of Organization for the Prohibition of Chemical Weapons. Summary report of the work OPCW Fact-Finding Mission in Syria covering the period from 3 to 31 May 2014. S/2015/138

Report of the OPCW fact-Finding Mission in Syria regarding an alleged incident in Khan Shaykhun, Syrian Arab Republic April 2017. S/2017/567, 30 June 2017

Report of the OPCW fact-Finding Mission in Syria regarding an alleged incident in Khan Shaykhun, Syrian Arab Republic April 2017. S/2017/567, 30 June 2017

Report of the United Nations Mission to Investigate Allegations of the use of Chemical Weapons in the Syrian Arab Republic on the alleged use of chemical weapons in the Ghouta area of Damascus on 21 August 2013. A/67/997/ – S/2013/553, 16 September 2013

United Nations Secretary-General, Report of the United Nations Mission to Investigate Allegations of the Use of Chemical Weapons in the Syrian Arab Republic on the alleged use of chemical weapons in the Ghouta area of Damascus on 21 August 2013, S/2013/553, 16 September 2013.

Report of the United Nations Mission to Investigate Allegations of the use of Chemical Weapons in the Syrian Arab Republic on the alleged use of chemical weapons in the Ghouta area of Damascus on 21 August 2013. A/67/997/ – S/2013/553, 16 September 2013

Russian response: ‘Statement by the Delegation of the Russian Federation at the Forty-Eighth Meeting of the Executive Council’, EC-M-48/NAT.1, 21 January 2015. ‘Letter dated 31 October 2017 from the Permanent Representative of the Russian Federation to the United Nations addressed to the Secretary-General’, S/2017/918, 6 November 2017

Literature and other analysis: Brett Edwards and Mattia Cacciatori, ‘The politics of international chemical weapon justice: The case of Syria, 2011–2017’, Contemporary Security Policy, vol. 39, no. 2 (2018).

Christopher A. Bidwell and Randall S. Murch, ‘Attribution: Use of microbial forensics in cases involving illicit programs and/or use’, Presentation to the BWC Meeting of Experts, Geneva, 12 August 2015.

Attacks on Ghouta: Analysis of the Alleged use of chemical weapons in Syria. Human Rights Watch, 10 September 2013.