Fog of War
The final months of the battle for Aleppo were marked by frequent reports of chemical weapon attacks against opposition-controlled areas, both inside and surrounding the city. Again, this pattern had already been played out elsewhere in Syria and has every likelihood of continuing.
Since the Sarin attacks in Damascus on August 21, 2013, there have been dozens of reports of chemical weapon attacks across Syria using chlorine, sarin, mustard gas, and other agents. In August 2016, the third report of the Organization for the Prohibition of Chemical Weapons-United Nations (OPCW/UN) Joint Investigative Mechanism concluded that Syrian government forces had used chlorine gas in two attacks, and had probably committed several more, between April 2014 and September 2015, including in cases where evidence had been removed; it also found that ISIS had used mustard gas in at least one attack.
The attacks detailed in the OPCW/UN report, and many additional attacks reported and documented by opposition groups, used helicopter-dropped “barrel bombs” holding cylinders of chlorine gas. The second half of 2016 saw at least ten reported chemical attacks, of which six could be verified, in Aleppo city itself. They shared many characteristics with the attacks in the OPCW/UN report, including the use of helicopters and gas cylinders, but also some differences.
Each State Party to this Convention undertakes never under any circumstances:
(a) To develop, produce, otherwise acquire, stockpile or retain chemical weapons, or transfer, directly or indirectly, chemical weapons to anyone;
(b) To use chemical weapons;
(c) To engage in any military preparations to use chemical weapons;
(d) To assist, encourage or induce, in any way, anyone to engage in any activity prohibited to a State Party under this Convention.
Chemical Weapons Convention, Article I
Even as the OPCW-UN were publishing their report in August 2016, fresh allegations of chemical weapons attacks were emerging in Syria, including in opposition-held east Aleppo. At the start of August two attacks were reported in the city, one on August 2, and a second on August 10.
In the August 10 attack, victims reported they had been hit by a barrel bomb containing chlorine gas dropped from a helicopter, a mode of attack consistent with other reports of chlorine gas use by Syrian government forces. Over seventy individuals were reported injured in the attack, including approximately thirty young children; three deaths were reported, including two children. The UN’s Syria Envoy, Staffan de Mistura said: “There seems to be a lot of evidence that it did take place.”
A further attack was reported on September 10, with over 150 victims transferred for treatment in local medical facilities. Multiple witnesses reported the use of helicopters to drop the bomb, as well as the distinctive smell of chlorine at the attack site. Two deaths were reported from the attack, one of them a 13-year-old child. al-Quds hospital treated many victims of the attack, sharing photographs of victims being treated on its Facebook page.
A medical report provided to Bellingcat by doctors at the al-Quds hospital listed the details of the victims: seventy-one patients treated as a result of the attack, including sixteen children below the age of five, twenty children between the ages of six and eighteen, and one pregnant woman. The report also stated that the victims were treated for exposure to chlorine.
The identification of chlorine as the agent is consistent with other reports, including statements recorded by various organizations and individuals working in the area. In a video published online by the White Helmets, a rescuer described the smell of chlorine at the attack site; American pro-opposition journalist Bilal Abdul Kareem produced a video from the attack site stating “The smell of chlorine is very strong here”; and in a video from the SMART News Agency filmed at the entrance to the al-Quds hospital, one man said that he found one of the victims and they smelt of chlorine.

Video footage was also published showing the remains of the gas cylinders allegedly used in the attack. These were notably similar to the type used in the attack of August 10, 2016. One civilian in the video stated that “men, women and children were taken to the hospital as a result of the chemical attack. More than 50 people were transferred to the hospital. There are no bases for fighting groups in this area, it’s mainly inhabited by civilians.”


In the final weeks of the siege of Aleppo, there was a noticeable uptick in the number of reports of chemical weapon attacks against opposition areas in and around the city. At least ten chlorine attacks were reported in Aleppo city between October and early December, with the remains of yellow chlorine gas cylinders, as documented at other sites over the preceding two and half years across Syria, recorded by local activists at many of the sites. The Syrian Archive project has verified and entered video pertaining to six attacks in Aleppo city during the last six months of 2016.
Not all of the attacks were well-documented with video or open source records. Some attacks, however, left a larger footprint, making it easier to examine the veracity of the claims. For example, an attack in the suburb of Hanano on November 18 was reported to have killed one person and injured five others. A number of videos, images, and testimonies of this attack are available online and have been examined in detail.
Several videos purport to show the aftermath of the attack, the remains of the cylinder, and children being treated in a hospital for respiratory issues as a result of the attack.


On November 20, a chlorine bomb was said to have been dropped on the al-Bab road neighborhood. Videos of the attack itself, and the resulting injuries, are limited, but subsequent footage from the site showed a chlorine gas cylinder with its labels intact.

In another attack on November 20, a man, his wife, and their four children were reported to have turned blue by the time rescuers got to them, after a barrel bomb was said to have fallen on their home. Videos and other open source information are available and appear to verify the claims.
November 23 brought further alleged attacks, this time in the al-Jazmati and Ard al-Hamra neighborhoods, with limited injuries, according to the material available online. Two days later, Sheikh Maqsoud was allegedly hit with mustard gas by Ahrar al-Sham and Jabhat Fateh al-Sham forces, killing six and injuring fifteen, though no videos of the attack or the weapons used are available to verify the claims.

These later attacks were rather unusual as, unlike in previous attacks, the chlorine cylinders were not dropped inside barrel-bomb casings. In many earlier attacks, chlorine-filled cylinders had been placed inside the casings of explosive barrel bombs in various configurations. In the November and December Aleppo attacks, no casing was apparent. This change may be the result of the destruction of a suspected barrel-bomb factory in the summer of 2016. Regardless, the end result was the same: the use of chlorine gas as a chemical weapon against opposition-controlled Aleppo.
The frequency of the reports of these chlorine attacks on Aleppo in the last days of the siege is noteworthy. According to paragraph 81 of the OPCW/UN report, monitors received allegations of forty-one chlorine attacks across the whole of Syria in the eight months between December 2015 and August 2016 (out of 131 alleged chemical attacks). According to witness accounts, the few remaining square miles of opposition-held Aleppo suffered at least ten chlorine attacks in the six weeks between mid-November and the end of the siege. In other words, east Aleppo alone suffered as many attacks in six weeks as the whole of the rest of the country had suffered, on average, in two months.