The Khan Shaykhun chemical attack took place on 4 April 2017 on the town of Khan Shaykhun in the Idlib Governorate of Syria. The town was reported to have been struck by an airstrike by government forces followed by massive civilian chemical poisoning. The release of a toxic gas, which included sarin, or a similar substance, killed at least 89 people and injured more than 541, according to the opposition Idlib Health Directorate. The attack was the deadliest use of chemical weapons in the Syrian civil war since the Ghouta chemical attack in 2013.
The OPCW-UN Joint Investigative Mechanism attributed the responsibility of the attack to the Syrian government. The OPCW-UN JIM described chemicals that it said linked the sarin used to the Syrian government: "The samples from Khan Shaykhun contain the three types of marker chemicals described above: PF6 [HFP], isopropyl phosphates and isopropyl phosphorofluoridates. Their presence is a strong indicator that the sarin disseminated in Khan Shaykhun was produced from DF from the Syrian Arab Republic stockpile."
The governments of the United States, United Kingdom, Turkey, Saudi Arabia, France, and Israel as well as Human Rights Watch attributed the attack to the forces of Syrian President Bashar al-Assad. The Syrian government said the attack was a "fabrication" while the Russian government said that the incident was staged.
On 7 April, the United States launched 59 cruise missiles at Shayrat Air Base, which U.S. intelligence cited as the source of the attack.
Background
Use of chemical weapons in the Syrian Civil War has been confirmed by the local sources in Syria and by the United Nations. Deadly attacks by chemical weapons during the war include the Ghouta attack in the suburbs of Damascus in August 2013 and the Khan al-Assal attack in the suburbs of Aleppo in March 2013. While no party took responsibility for the chemical attacks, a U.N. fact-finding mission and a UNHRC Commission of Inquiry have both investigated the attacks.
The U.N. mission found likely use of the nerve agent sarin in the case of Khan al-Asal (19 March 2013), Saraqib (29 April 2013), Ghouta (21 August 2013), Jobar (24 August 2013) and Ashrafiyat Sahnaya (25 August 2013). The UNHRC commission later confirmed the use of sarin in the Khan al-Asal, Saraqib and Ghouta attacks, but did not mention the Jobar and the Ashrafiyat Sahnaya attacks. The UNHRC commission also found the sarin used in the Khan al-Asal attack bore "the same unique hallmarks" as the sarin used in the Ghouta attack and indicated the perpetrators likely had access to chemicals from the Syrian Army's stockpile. Those attacks prompted the international community to pressure disarmament of the Syrian Armed Forces from chemical weapons, which was executed during 2014. Despite the disarmament process, dozens of incidents with suspected use of chemical weapons followed throughout Syria, the majority being attributed to anti-government fighters, in particular the Al Qaeda affiliate Al Nusra Front.
In August and October 2016, United Nations reports explicitly blamed the Syrian military of Bashar al-Assad for dropping chlorine bombs on the towns of Talmenes on 21 April 2014, Sarmin on 16 March 2015. and Qmenas, also on 16 March 2015. Several other attacks have been alleged, reported and/or investigated. In December 2016, at least 53 people were killed in an alleged chemical weapons attack in ISIL-held villages near Uqairabat that bore similarities to the Ghouta attack, with none of the dead having blast injuries.
The immediate context for the Khan Shaykhun attack was the intensified aerial campaign in March and April 2017 by the government and its Russian ally to gain control of Kafr Zeita, Murek and al-Lataminah, then the three remaining rebel-held towns in the northern Hama Governorate. (See Hama offensive (March–April 2017).) On 30 March 2017, an airstrike hit al-Lataminah, around 15 kilometers (9 miles) from Khan Shaykhun. More than 70 people in the area were then exposed to an unidentified chemical agent and showed symptoms of nausea, agitation, foaming, muscle spasm, and miosis (constriction of the pupil of the eye). Cardiac arrest occurred in two of the victims and an orthopedic doctor died. On 3 April 2017, one day before the Khan Shaykhun attack, a "regime aircraft" allegedly carried out a similar chlorine gas attack on Al-Habit, a nearby village, injuring dozens and killing two children.
Attack
The attack took place around 6:30 a.m. local time on 4 April, before most children and parents had left for school or work. Witnesses reported smelling a strange odor about ten minutes after a rocket attack and airstrike, followed by visible symptoms of poisoning. White Helmets volunteers reported four unusually weak explosions. Victims were treated at al-Rahma hospital in Idlib. Medical workers and witnesses said the attack was different than the chlorine gas attacks they had experienced in the past, in which the chlorine gas usually killed a few people in confined spaces and buildings. In contrast, in this attack, many people died outside. Furthermore, the victims exhibited pinpoint pupils, a sign of contact with nerve agents and sarin specifically. Other symptoms reported included coldness in the extremities, decreased heart rate, and low blood pressure, convulsions, foaming at the mouth or vomit, and respiratory paralysis. Some first responders became ill when they came into contact with the victims.
Rescue workers gathered soil and tissue samples and sent them to Western intelligence officials for analysis. On 6 April, the Turkish Ministry of Health, which had conducted tests on people transported to Turkey, said it had identified the chemical used in the attack as sarin, citing lung damage found in victims. On 11 April, Turkish Minister of Health Recep Akdağ stated that isopropyl methylphosphonic acid—a known byproduct of sarin reacting with other compounds—was "identified in the blood and urine tests conducted on samples taken from the victims". Tests by British scientists of samples found at the scene indicated the chemical involved was "sarin or a sarin-like substance".
The Guardian's Kareem Shaheen, the first reporter from western media to visit the town after the attack, photographed the crater where the chemical weapon was reported to have hit an apparently abandoned warehouse and silos near the crater.
Casualties
Medical sources in Idlib in the immediate aftermath of the attack reported more than 58 people, including 11 children, were killed and over 300 were wounded. Test results of samples collected from ten of them indicated they had been exposed to sarin or a sarin-like substance.
By 7:30 a.m. EEST 100 wounded people arrived at a local field hospital. The opposition minister of health, Mohamad Firas al-Jundi, said victims experienced suffocation, fluid in the lungs, foaming at the mouth, unconsciousness, spasm, and paralysis.
A few hours after the attack, a nearby clinic treating victims was hit by an airstrike, with reports that Russians bombed the hospital with the victims in an attempt to destroy the evidence. The area's largest hospital was bombed two days prior. According to Dr. Abdel Hay Tennari, who treated 22 victims of the attack, the symptoms of victims corresponded to symptoms of exposure to sarin. Patients who received pralidoxime, an antidote of sarin, reportedly stabilized their medical state in around an hour. Médecins Sans Frontières visited Bab Al Hawa hospital where they determined symptoms consistent with sarin. They also visited other hospitals where victims were taken and reported, "that victims smelled of bleach, suggesting they had been exposed to chlorine." They concluded that the "reports strongly suggest that victims of the attack on Khan Sheikhoun were exposed to at least two different chemical agents."
On 5 April, local doctors and rescue workers at the scene said the number of dead had risen to 74, with 600 injured, and later that day The Daily Telegraph reported 86 deaths, including 30 children, and noted the death toll was rising as so many had died in their homes and only taken to hospitals later. Turkish President Recep Tayyip Erdoğan and French Ambassador to the United Nations François Delattre said over 100 had died. On 7 April, the opposition Idlib Health Directorate said 89 had died, 18 women and 33 children. On 9 May 2017, a report from CNN said the attack killed 92 people in all.
Responsibility
On 6 September 2017, the UN Office of the High Commissioner for Human Rights' Independent International Commission of Inquiry on the Syrian Arab Republic concluded that a Syrian Air Force aircraft was responsible the sarin attack, saying "the Syrian air force used sarin in Khan Sheikhoun, Idlib, killing dozens, the majority of whom were women and children". It dismissed the Syrian and Russian claim that a bomb struck an opposition chemical weapons depot on the outskirts of the northern town as “fabricated”. The report found that a Sukhoi 22 jet, which is only flown by the Syrian airforce, had carried out four airstrikes at 6.45am on 4 April. Three bombs carried conventional explosives, but one, which struck a road, carried the deadly nerve agent, which was carried as far as 600 metres away on a gentle wind.
“Weather conditions at 6.45am on 4 April were ideal for delivering a chemical weapon,” the report said. “The wind speed was just over 3km/h, with no rain and practically no cloud cover. Under such conditions, the agent cloud would have drifted slowly downhill following the terrain features at the location.”
The Assad government has repeatedly denied using chemical weapons, but the report said the Syrian government's version of events, that an unknown weapons depot had been hit, was “extremely unlikely”. It said sarin stored in such circumstances would have mostly burned off or been absorbed by rubble, and that there was no evidence of the building being contaminated.
A visit by The Guardian to Khan Sheikhun two days after the attack revealed that the site officials claimed had been hit had been empty for many months, and contained only animal feed and a volleyball net. Witnesses described the frantic aftermath of a series of airstrikes, which overwhelmed the limited capacity of local medics and rescue workers. This finding was confirmed in a report released on 26 October 2017 by the OPCW-UN Joint Investigative Mechanism.
Many governments, such as the United States and some European countries and the Gulf Cooperation Council attributed the attack to the Syrian government. According to investigation by Human Rights Watch, the attack was conducted by Syrian government forces from the air using Soviet-made KhAB-250 aerial bombs designed to deliver sarin. The investigative journalism website Bellingcat suggested Russia may have inadvertently provided evidence of the Syrian government's use of the M4000 chemical bomb. The Syrian government denied any involvement. Immediately following the attacks, Russia said the Syrian Air Force had struck Khan Shaykhun "between 11:30am and 12:30pm local time" on 4 April, but that the target had been "a large terrorist ammunition depot" on its eastern outskirts. "On the territory of the depot, there were workshops which produced chemical warfare munitions", and following the OPCW conclusions, in October 2017, it strongly disputed the conclusion that the Syrian government was responsible. The UN Security Council session unanimously declared the need for an investigation of the chemical attack. According to an OPCW report, an investigation into the attack was concluded and released on 29 June 2017, which confirmed the use of sarin gas, or a similar substance.
The United Kingdom’s assessment is that it is almost certain that the Syrian Government was responsible for a sarin attack on Khan Shaykhun on 4 April. (...) There is no evidence to suggest that any party to the conflict in Syria, other than the Syrian Government, has access to a complex nerve agent such as sarin. We note that the FFM’s report refers to testimony from witnesses describing the presence of jets in the area at the time of the attack. Only the Syrian Air Force has the capability to launch a chemical weapons attack from aircraft, and it has already been condemned by this Council for having been found to have used chemical weapons, deployed from aircraft, on at least three occasions in 2014 and 2015.
— Sir Geoffrey Adams, UK Permanent Representative to the OPCW,
In May 2026, an OPCW expert team, supported by the Syrian authorities, discovered significant quantities of undeclared chemical weapons, including rockets and aerial bombs, at high-interest sites in northern coastal and central Syria, including aerial bombs of the same type as those used in the Khan Shaykhun attack.
Claims by the Syrian government, Syrian opposition and Russian government
Syrian opposition claims
According to the Idlib Media Centre, the chemical agent had the characteristics of sarin. The National Coalition for Syrian Revolutionary and Opposition Forces accused the Syrian government and the Syrian Armed Forces of carrying out the attack and called for an immediate investigation by the United Nations Security Council. The opposition groups said the Syrian air force dropped chemical bombs on a civilian population.