A/HRC/36/55 the gathering as strictly religious, and explained that most attendees were Al-Jinah residents, and that many of them were internally displaced persons, with the exception of some residents from neighbouring towns, such as Atarib. 61. Some interviewees, however, noted an Hay’at Tahrir al-Sham presence in the village, and it cannot be ruled out that some members of that group may have attended the gathering. In this regard, the Commission notes that even though bombs designed to inflict low collateral damage were used, the United States targeting team lacked an understanding of the actual target, including that it was part of a mosque where worshippers gathered to pray every Thursday. Moreover, although the targeting team had information on the target three days prior to the strike, it did not undertake additional verification of target activities in that period, which would be expected were it known to be a mosque. The Commission therefore concludes that United States forces failed to take all feasible precautions to avoid or minimize incidental loss of civilian life, injury to civilians and damage to civilian objects, in violation of international humanitarian law. B. Medical facilities 62. Since its inception, attacks against medical facilities and medical personnel have been a tragic hallmark of the Syrian conflict. In an attempt to protect health-care infrastructure, personnel and patients, many hospitals and clinics in areas under opposition control have relocated underground, operating from reinforced basements and, sometimes, from caves dug into mountains. “Cave hospitals” are typically located on the outskirts of Syrian towns, without any other buildings in their vicinity. While such measures are intended to afford additional protection, intentional attacks against underground and cave hospitals continue to transpire. 63. Between March and April, when Syrian and Russian forces heightened their aerial campaign to gain control of Kafr Zeita, Murek and Al-Latamneh, the only remaining towns in northern Hamah controlled by Hay’at Tahrir al-Sham and armed groups, a surge of air strikes on medical facilities in northern Hamah and southern Idlib were carried out. These attacks took place shortly before and after Syrian forces used chemical weapons in the same area (see paras. 69-70 and 72-77 below), thus preventing victims of chemical attacks from obtaining essential medical treatment. In one of the attacks, pro-Government forces used chlorine, while in another they used cluster incendiary munitions. The Commission has previously reported on pro-Government forces using such weapons to attack both medical facilities and individuals providing medical care in eastern Aleppo city. 13 64. In the afternoon of 5 March, an air strike hit the Al-Sham underground hospital in Kafr Nabl, southern Idlib, destroying two floors and a generator and injuring one hospital worker. Interviewees recalled that the hospital had been rendered out of service as a result of an air strike on 25 February, noting that the number of civilian casualties would have otherwise been significantly higher. On 25 March, at approximately 1 p.m., a Syrian air force helicopter dropped a barrel bomb on Al-Latamneh hospital, killing three civilian men — a surgeon and two patients — and injuring a number of staff and patients. Photos of remnants provided to the Commission depict an improvised chlorine bomb. Eyewitnesses heard the bomb make only a slight noise before releasing a yellow/greenish smoke that smelled strongly of cleaning agents. The use of chlorine is further corroborated by symptoms reported: at least 32 persons were injured as a result of the attack, most of them suffering from irritated throats and eyes, difficulties breathing, vomiting and frothing of the mouth. One interviewee said that some of the injured were armed group fighters. In this regard, the Commission notes that the use of chemical weapons is prohibited in all circumstances, including when a military objective is present. 65. On 2 April, the Maarat al-Numan national hospital was struck by at least three delayed-fuse aerial bombs (see annex II, para. 15). Two days later, an air strike hit the AlRahma medical point in Khan Shaykhun (see annex II, paras. 17-18). A clinic in Heish, 13 See A/HRC/34/64, paras. 33-35. 13