Syria Chemical Overview

This page is part of the Syria Country Profile.

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Syrian efforts to acquire and maintain an arsenal of chemical weapons date to the mid-1970s. Regional security concerns, most notably Syria’s adversarial relationship with Israel, were the motivations behind Syria’s chemical weapons program. The Syrian regime’s chemical weapons have been used to devastating effect against both combatants and civilians during the Syrian Civil War.

For decades, Syria elected not to join the Chemical Weapons Convention (CWC), claiming it could not unilaterally renounce chemical weapons as long as Israel continued to pose a threat to its security. ¹ In the fall of 2013, however, following a United Nations investigation into the use of chemical weapons in Syria, the Assad regime acceded to the CWC and declared its chemical weapons stockpiles to the Organization for the Prohibition of Chemical Weapons (OPCW). ² The confidential declaration showed that Syria possessed large stockpiles of sulfur mustard, sarin, and VX nerve gas, as well as various precursor chemicals. ³ Syria’s declared chemical weapons stockpile was destroyed by January 2016, but Western officials and the OPCW doubted that the regime had completely and accurately declared its entire stockpile. ⁴ Continued chemical weapons attacks, including the use of chlorine and a nerve agent in Douma on 7 April 2018, as well as reported North Korean assistance to an enduring Syrian chemical weapons program, suggest that chemical weapons remain a threat inside the country. ⁵

1972 to 1986: The Israeli Threat and Initial CW Imports

Defensive CW equipment was among the first CW-related imports by Syria in the 1970s and 1980s. Imported protective capabilities included military vehicles from the Soviet Union fitted with chemical protection systems, as well as a full range of decontamination equipment. ⁶ Syria also purchased more than 11,000 Chinese MF-11 protective masks. ⁷

Press and U.S. government sources indicate that Syria first obtained chemical weapons from Egypt on the eve of its attack on Israel in October 1973. ⁸ Reports that Israeli troops captured stockpiles of Syrian chemical weapons support the view that Syrian combat troops received these weapons during the Yom Kippur war. ⁹ Notably, although Syrian forces suffered severe defeat, at no point did they deploy chemical weapons. However, Syrian-born security analyst M. Zuhair Diab and Israeli military analysts suggested that Syria may have planned to use its chemical arsenal only in the event of a total military collapse. ¹⁰

Suboptimal military coordination among Syria, Egypt, and Iraq during the 1973 Yom Kippur War revealed fissures in Arab unity against Israel. The 1979 Egyptian-Israeli Peace Treaty deprived Syria of an important military ally against the Israeli threat, driving it to pursue greater military self-sufficiency. M. Zuhair Diab noted that the near-disastrous clashes with Israeli forces during the Israeli invasion of Lebanon in 1982 exposed Syria’s land and air vulnerabilities, and further motivated Syria’s military to acquire chemical weapons. ¹¹

Other regional developments may have motivated Syria’s pursuit of a CW capability, including water-sharing conflicts with Turkey over the Euphrates River, and Turkish allegations of Syrian support for Kurdish terrorism. ¹² Perhaps more directly troublesome to Syrian leadership, the Soviet Union chose to support Iran during the Iran-Iraq War, weakening Syria’s partnership with the USSR and further isolating Syria. ¹³ The combination of increased political isolation and observed military deficiencies vis-à-vis Israel provided incentives for Syria to develop a self-sufficient CW capability.

1986 to 2011: Building CW Self-Sufficiency

Despite Israeli media reports that Syria began developing an indigenous chemical production capability as early as 1971, most reports indicate that Syria’s CW production capability came online sometime in the mid-1980s. ¹⁴ In 1983, a U.S. Special National Intelligence Estimate first identified a Syrian CW production facility. A 2014 disclosure by the British government revealed that by 1986 Syria had obtained hundreds of tons of precursor chemicals, including trimethyl phosphite, dimethyl phosphite and hydrogen fluoride from the United Kingdom, and other technology for developing nerve agents such as sarin gas. ¹⁵ By 1990, both media and statements by U.S. officials indicated that Syria had converted several agrochemical factories into sarin production facilities. By 1997, both U.S. and Israeli sources claimed that Syria’s CW program included production facilities in Damascus, Homs, and Aleppo and could produce sarin, mustard, and potentially VX. ¹⁶ Reports throughout the 1990s pointed to continuing Syrian work on VX agents, but also indicated a lack of success. ¹⁷

The United States has banned the sale of sarin and mustard precursors to Syria since the 1980s. ¹⁸ However, by the early 1990’s, reports of illicit trade began to emerge. In 1996, Russian authorities charged retired Lieutenant General Anatoliy Kuntsevich with shipping 800-kilograms of precursor chemicals to Syria. ¹⁹ Although these charges were eventually dropped, Israeli press reported that Kuntsevich later admitted to the transfer of nerve agent precursors. ²⁰

From 2002 to 2006, reports from the U.S. Director of Central Intelligence repeated that “Damascus already held a stockpile of the nerve agent sarin, but apparently tried to develop more toxic and persistent nerve agents.” ²¹ The 2009 and 2010 versions of this report drew similar conclusions, including that “Syria remains dependent on foreign sources for key elements of its CW program, including precursor chemicals.” ²² Relatively few open source reports of Syrian tests on CW agents or delivery systems emerged during this time. ²³ The most recent publicly described test, a Syrian missile test in July 2001, probably involved the use of a simulated chemical warhead. ²⁴ During the early 2000s, Syria’s CW program maintained a very low profile, although Jane’s Defense continued to report on foreign support for the development of chemical warheads for Scud missiles and other delivery systems. ²⁵

2011 to 2013: Outbreak of Civil War and Initial CW Use

The outbreak of civil unrest in late 2011 raised questions about both the security of Syria’s chemical weapons sites and the potential use or transfer of these weapons. On 23 July 2012, Syrian Foreign Ministry spokesman Jihad Makdissi stated that Syria would never use “any chemical and biological weapons … inside Syria…that the Syrian army was storing …all stocks of these weapons…” securely, and that such weapons would only be used in the event of “external aggression.” ²⁶ Subsequently, Makdissi tried to walk back this apparent acknowledgement of Syria’s possession of chemical and biological weapons, something Syria had previously denied. ²⁷

As the conflict intensified, the international community became increasingly concerned that Syrian President Assad might use chemical weapons amid Syria’s deteriorating security situation and rebel gains. Between late November and early December 2012, Western intelligence agencies obtained clear evidence that Syrian government units were preparing chemical weapons for potential use, including mixing precursor chemicals and loading chemical weapons onto special military transport vehicles. ²⁸ The first reported use of chemical weapons occurred in late December 2012 in Homs, Syria. Civilians were treated for symptoms of chemical exposure such as nausea, vomiting, difficulty breathing, blurred vision, lack of muscle control, convulsions, and loss of consciousness. ²⁹

A few months later, on 19 March 2013, allegations arose concerning a chemical weapons attack in the village of Khan al-Assal in the Aleppo province. According to the Assad regime, a rocket spewing toxic gas caused 26 fatalities and more than 100 injuries. Both the Assad regime and Syrian rebels denied responsibility for the alleged attack. ³⁰ At the request of the Syrian Government, United Nations Secretary-General Ban Ki-Moon appointed Åke Sellström, on 27 March 2013, to head a fact-finding mission to investigate the incident. Initially, the Assad Government denied the team entrance into Syria, stalling for four months before granting UN inspectors permission to visit the country on 31 July 2013. ³¹

On the morning of 21 August 2013, video footage emerged of a chemical weapons attack in Ghouta, just outside of Damascus. According to initial reports and video footage, the attack involved an organized strike on a large area that utilized rockets as dispersal mechanisms. Hospitals and make-shift medical centers reported patients suffering from convulsions, immobilization, breathing difficulties, dilated pupils, cold limbs, and foaming at the mouth. Doctors Without Borders reported that three hospitals within its network confirmed 355 deaths and approximately 3,600 casualties with neurotoxic symptoms, while a U.S. government assessment placed the number of dead at 1,429 people. ³² The Syrian government eventually granted the UN inspection team access to areas of Ghouta after stalling for five days. ³³ In the immediate aftermath of the attack, the United States tried to rally support to conduct limited military strikes against Assad’s forces, but was only able to gain French support.

2013 to 2014: Dismantling Syria’s CW Stockpile

As the U.S. Congress prepared to vote on whether to attack Syria, on 10 September 2013, the Syrian Government made the unexpected decision to place its chemical weapons stockpile under international control, and committed to joining the Chemical Weapons Convention. Four days later, Russia and the United States reached a deal on a framework to eliminate Syria’s chemical weapons. ³⁴ The framework called for Syria to submit a comprehensive list of its chemical weapons within one week, for inspectors to return to Syria by November 2013, and for the destruction of all chemical weapons to take place by mid-2014. ³⁵ Syria met its initial obligations by providing two lists of its chemical weapons. ³⁶ According to the OPCW’s initial findings, the Syrian arsenal included 1,000 metric tons of Category I chemical weapons, 290 tons of Category II chemicals, and 1,230 Category III unfilled delivery systems such as rockets. ³⁷

Two days after the framework was agreed upon, the United Nations released its much-anticipated report, stating that the UN had “clear and convincing” evidence that sarin gas was used in the 21 August attacks in Ghouta. ³⁸ While the report did not attribute responsibility for the attack, report details, such as the use of M-14 and 330m rocket artillery and estimated trajectories, suggested that the Assad regime was responsible for the attacks, as the rebels did not possess the type of rockets used. ³⁹ The United States, the United Kingdom, and France accepted the UN report as confirmation of the Assad regime’s role in the attacks but Russia stated that the report was “distorted” and “one-sided,” and maintained that the Assad regime did not conduct the attacks. ⁴⁰

On 27 September 2013, the OPCW adopted a decision on the destruction of Syria’s chemical weapons, which called for the destruction of all chemical weapons production and mixing facilities by 1 November 2013, and the destruction of all chemical weapons by mid-2014. ⁴¹ On 14 October 2013, the Chemical Weapons Convention entered into force for Syria, and by 31 October, Syria had met the Phase I deadline of eliminating all of its production and mixing capabilities. ⁴²

Destruction of Syria’s declared chemical weapons took place outside Syrian territory. On 7 July 2014, the United States began neutralizing 600 tons of sulfur mustard agent and DF, a sarin gas precursor, aboard the U.S. Cape Ray, a cargo ship equipped with a hydrolysis system stationed in the Mediterranean Sea. ⁴³ An additional 200 tons of various chemical precursors were sent to the United Kingdom for destruction. ⁴⁴ On 4 January 2016, the OPCW announced the complete destruction of Syria’s 1,328 metric tons of declared chemical weapons agents. ⁴⁵

2014-2017: Continued CW Use and Undeclared Capabilities

While the destruction of Syria’s declared chemical weapons was hailed as a great achievement, questions remained over the completeness of Syria’s chemical weapons declaration. Samples taken by the OPCW at the Syrian military research site “Institute 3000” (in May 2014 and January 2016), revealed the presence of DIPAE sulfonic acid and DIPA ethanol, chemicals present in the initial stages of VX breakdown. Inspectors also found traces of pinacolyl alcohol at the facility, which is a precursor for the nerve agent soman and has no peaceful uses. ⁴⁶ In May 2015, it was revealed that OPCW inspectors found traces of sarin and VX at an undeclared military facility during testing in December 2014 and January 2015. ⁴⁷

Chemical attacks steadily continued in the wake of the OPCW-UN mission to dismantle Syria’s chemical weapons apparatus. Medical aid groups estimate that there have been 198 chemical attacks in the country since 2012, with a majority occurring since the OPCW-UN mission. ⁴⁸ Heated debate over attributing responsibility for chemical weapons attacks in Syria led to the creation of a new investigative body- the OPCW-UN Joint Investigative Mechanism (JIM). Established on 7 August 2015 by the UN Security Council, the body’s mandate was to identify the perpetrators, organizers, sponsors, or other parties involved in the use of chemical weapons in Syria. ⁴⁹

Reports emerged later in August of the use of mustard agent by ISIS against Kurdish forces in Iraq and Northern Syria, as well as against civilians in the town of Marea, Syria. ⁵⁰ It was suggested that ISIS may have obtained the mustard agent from clandestine Syrian government chemical weapons caches, giving the international community another reason to doubt the completeness of Syria’s initial chemical weapons declarations. ⁵¹ On 24 August 2016 and 21 October 2016, the JIM released its first two substantive reports confirming ISIS’s use of sulfur mustard in Marea on 21 August 2015. In the same reports, the JIM formally attributed the chlorine gas attacks in 2014 and 2015 to the Assad regime. ⁵² ISIS deployed sulfur mustard again on 16 September 2016 in the village of Um-Housh, north of Aleppo. An OPCW fact finding mission confirmed the presence of sulfur mustard in a report dated 1 May 2017, and the JIM later confirmed ISIS as the perpetrator. ⁵³

On 13 December 2016, it was reported that an alleged chemical gas attack killed at least 93 people in villages located in ISIS-controlled territory, west of Palmyra. Witnesses claimed that the smell of the gas “was distinct from the smell of chlorine.” Reported symptoms included coughing, foaming at the mouth, suffocation, convulsions, involuntary urination, and constricted irises, all possible indicators of exposure to nerve agents. ⁵⁴ The OPCW released a statement calling the allegations concerning and said that its fact-finding mission would investigate, though a report has yet to be released as of early 2018. ⁵⁵

On 12 January 2017, the U.S. Department of the Treasury announced the first set of U.S. sanctions specifically related to the regime’s use of chemical weapons. It sanctioned eighteen senior Syrian officials in response to the findings of the Joint Investigative Mechanism that the Syrian regime used chlorine as a weapon against civilians. ⁵⁶ A month later, on 28 February 2017, the UN Security Council failed to adopt a draft resolution to impose sanctions on entities involved in the production or use of chemical weapons in Syria. China, Bolivia and the Russian Federation vetoed the draft resolution. The Russian representative slammed the resolution and the work of the JIM as politically motivated and “laying the groundwork for regime change” in Syria. ⁵⁷

On 4 April 2017, there were reports of a sarin gas attack on the village of Khan Sheikhoun, 30 miles south of the city of Idlib. Hospitals and clinics treating victims of the alleged chemical attack were subsequently bombed. The Syrian regime denied responsibility but a declassified U.S. National Security Council report claimed Syrian government forces launched the attack, which killed between 80 and 100 people, many of them children. ⁵⁸ Two days later, the United States launched 59 Tomahawk missiles at Al-Shayrat airbase, after determining it was the location from which the chemical attack was launched. ⁵⁹

In a report released on 30 June 2017, the OPCW fact-finding mission concluded that sarin or a sarin-like substance was used in Khan Sheikhoun on 4 April. ⁶⁰ The JIM released the results of its own investigation fourth months later. In its report dated 26 October 2017, the JIM confirmed that sarin was used and attributed the attack to the Assad regime. The JIM also revealed that the sarin used in Khan Sheikhoun was likely manufactured from precursor chemicals found in the government’s original CW stockpiles- the same ones at the center of the 2014 OPCW-UN mission to dismantle Syria’s chemical weapons program. ⁶¹ Later, it emerged that the OPCW compared the sarin samples from Khan Sheikhoun to sarin samples from Ghouta and Khan al-Assal. It found matching chemical signatures in all three samples, linking the Syrian government to the Ghouta and Khan al-Assal attacks. ⁶²

On 6 November 2017, the OPCW fact-finding mission announced that during its investigation into the Khan Sheikhoun attack, it found credible evidence that sarin was also used in the town of Ltamenah on 30 March 2017. ⁶³

Following the publication of the OPCW and JIM reports, tensions rose between the United States and Russia. Russia criticized the work of the JIM, calling its investigation into the Khan Sheikhoun attack biased and “amateurish,” while the United States accused Russia of protecting Assad. ⁶⁴ Tensions peaked on 17 November 2017, when the UN Security Council failed to extend the mandate of the JIM, terminating the mechanism. Russia vetoed two resolutions to extend the mechanism, allowing it to expire. ⁶⁵ The UN Security Council has yet to replace the JIM as of April 2018. ⁶⁶ France, along with 30 other countries, launched the International Partnership Against Impunity for the Use of Chemical Weapons on 23 February 2018. The partnership does not replace the JIM but aims to facilitate cooperation and information sharing among states dedicated to combating chemical weapons use. ⁶⁷

In March 2018, the UN Panel of Experts tasked with investigating North Korean sanctions evasion released a report detailing cooperation between the two countries on Syria’s various WMD programs. According to the report, Syria received special resistance valves and thermometers associated with chemical weapons production, as well as 13 shipping containers full of acid-resistant tiles, which could be used inside a chemical factory. ⁶⁸ On 7 April 2018, reports of a large chemical weapons attack emerged from the rebel-held town of Douma, a suburb of Damascus. Eyewitness accounts from civilians and medical workers described individuals with symptoms indicating exposure to chlorine gas, as well as an unidentified nerve agent. Various monitoring groups put the death toll at around 49 individuals. The Syrian regime denied responsibility and blamed rebel groups in Eastern Ghouta for the attack. ⁶⁹ Russia and Iran tried to defend the Syrian government by denying that the attack occurred, and then shifting the blame to the Syrian Civil Defense Force (known as the White Helmets) and the United Kingdom. ⁷⁰ On 10 April 2018, The OPCW announced that it would deploy a fact-finding mission to Douma to clarify details of the attack, including the exact chemical agents used. ⁷¹ The same day, the UN Security Council voted on competing resolutions by the United States and Russia to revive a mechanism to investigate the use of chemical weapons in Syria. The Security Council failed to adopt either resolution. ⁷² In response to the attack on Douma, on 14 April 2018, the United States, the United Kingdom, and France carried out airstrikes against three targets associated with the regime’s chemical weapons program. The targets were a chemical weapons research and development center in the Barzeh district of Damascus, as well as two chemical weapons storage sites outside the city of Homs. ⁷³