A/HRC/34/64 increased use of these weapons disproportionately affected civilians by compounding the suffering of victims prevented from obtaining adequate treatment. 52. The Commission investigated numerous incidents of allegations of improvised chlorine bombs dropped from helicopters, which resulted in civilian casualties. In none of the incidents reviewed did information gathered suggest the involvement of Russian forces. Given that the incidents reported were all the result of air-delivered bombs, it is concluded that these attacks were carried out by Syrian air forces. The use of chlorine by Syrian forces follows a pattern observed in 2014 and 2015 (see S/2016/738). 53. In addition to violating the Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on Their Destruction (see annex I, para. 40), the use of chemical weapons in residential areas, including chlorine bombs which are incapable of distinguishing between civilian and military targets, constitute war crimes (ibid., paras. 41-42). 54. On 6 September, at approximately 1 p.m., an improvised chlorine bomb was airdelivered in al-Sukkari district. A man and a 13-year-old girl died as a result of asphyxiation, while more than 80 civilians suffered from the effects of chlorine inhalation. Eyewitnesses saw helicopters hovering in the sky when the bomb was dropped, while those in the vicinity began suffocating and their eyes became red shortly afterwards. Witnesses further reported a strong odour resembling domestic detergents. Available footage shows individuals, including women, children and an elderly man, receiving oxygen, and remnants of the improvised chemical munition. The attack was carried out by Syrian forces. 55. Between 8 and 12 December, reports of toxic chemicals being dropped in al-Kalasa neighbourhood emerged daily. One physician treating victims of the attack on 8 December in Al-Kalasa recalled he also treated patients from the Bustan al-Qasr and al-Firdous districts that day. Eyewitnesses saw bombs being dropped by helicopters at around 4 p.m. and a yellow gas leak from the barrels. A pungent accompanying odour was also reported. Thirty-five victims, including women and children, reportedly suffered from symptoms consistent with chlorine inhalation, including hypoxia, bronchospasms and respiratory failure. 56. On 9 December, at around midday, two improvised bombs with chlorine payloads were dropped in Al-Kalasa and Bustan al-Qasr. Thirty civilians suffered from effects consistent with chlorine exposure, and footage obtained confirms children struggling with shortness of breath and teary eyes. On 10 December, doctors reported treating patients from Bustan al-Qasr with similar symptoms. On this occasion, improvised chemical bombs were used directly on al-Hayat clinic, which had been treating victims of chlorine attacks over the previous days. Medical staff and patients suffered symptoms consistent with chlorine exposure, and footage and images assessed are consistent with an air-delivered improvised chlorine bomb. 57. From September onwards, an alarming number of incidents involving cluster munitions were also reported. Although the Syrian Arab Republic is not a party to the Convention on Cluster Munitions, the use of cluster munitions in densely populated areas is inherently indiscriminate (given the typically wide dispersal pattern and high dud rate, which continues to endanger civilians years after a cessation of hostilities) and therefore prohibited by customary international humanitarian law. For this reason, their use in cities such as eastern Aleppo constitutes the war crime of indiscriminate attacks in a civilian populated area (ibid., para. 44). 58. A resident of Karm al-Qaterji district reported being woken up by an explosion on 14 October, at around 4 a.m.. He and his brother went outside to find buildings on fire. While helping to put out the fire, they saw an aircraft drop a bomb that “exploded in the air” and released a number of sub-munitions, one of which killed the resident’s brother. 12