A/HRC/44/61 entire length of the M5 highway for first time since 2012. On 17 February, President Assad declared that the Syrian Arab Army had defeated militants and had liberated Aleppo Governorate after consolidating control over Aleppo’s western countryside. 14. Amid continued attacks on Turkish positions in Idlib Governorate, on 19 February, President Erdogan stated that a military operation in the north-west of the Syrian Arab Republic was imminent. The announcement came following unsuccessful negotiations between officials of the Russian Federation and of Turkey to de-escalate. On 27 February, tensions escalated after at least 33 Turkish soldiers were killed in an air strike. In response, Turkey launched Operation Spring Shield on the same day. During the first three days of the operation, the Turkish army conducted hundreds of strikes against positions held by Government forces, shot down two Syrian fixed-wing aircraft, put Nayrab military airport out of service and enabled the Syrian National Army16 to launch a ground offensive. 15. The killing of Turkish soldiers and the start of Operation Spring Shield further strained relations between the Russian Federation and Turkey. Nonetheless, both countries agreed on 5 March to establish a new ceasefire in Idlib following talks between Presidents Erdogan and Putin in Moscow. They agreed to cease all military actions along the line of contact in the Idlib de-escalation zone and establish a security corridor around the M4 highway. The agreement specified that the Russian Federation and Turkey would establish joint coordination centres and patrols. Turkey also clarified that the agreement would not alter previous arrangements and Turkish military observation posts in the north-west of the Syrian Arab Republic would remain in place. 16. While the ceasefire agreement led to a decrease in hostilities and a significant drop in civilian casualties, 17 the situation remained volatile. The Russian Federation reported ceasefire violations as low intensity shootings persisted and Hay’at Tahrir al-Sham terrorists announced that they would continue attacks against Government positions. By 28 May, the Russian Federation and Turkey had conducted 13 joint patrols on the M4 highway, which were often beset by clashes between Turkish forces, Hay’at Tahrir al-Sham and protesters, resulting in casualties. Ceasefire violations continued throughout April and May. 18 IV. Overview of the conduct of hostilities 17. During the period under review, battles over Idlib Governorate and western Aleppo left frontline localities near strategic locations in ruins and almost completely depopulated. Attacks were most often characterized by brief ground operations by the Syrian Arab Army and allies, coupled with prolonged aerial offensives by pro-Government forces. Overflight data obtained by the Commission indicated that at least 1,500 air strikes, predominantly airto-ground missiles and barrel bombs, had been launched on south-east Idlib and western Aleppo between 1 November 2019 and 5 March 2020, in addition to ground attacks and indirect fire, including rockets, artillery and mortars. 18. As they gradually ceded territory to pro-Government forces, armed groups and terrorist organizations also launched indiscriminate attacks against residential areas under Government control in western Aleppo. According to the Russian Federation, over 1,800 instances of shelling and more than 430 attacks involving heavy weapons by militants were reported from 9 January to 27 February.19 19. Given the intense fighting during the period, the Commission could not investigate all alleged unlawful attacks, but focused on 52 emblematic incidents, by all parties, that entailed civilian casualties and/or damage to civilian infrastructure. 16 17 18 19 4 A/HRC/42/51, para. 16; and A/HRC/43/57, para. 12. Data provided by the Office of the United Nations High Commissioner for Human Rights (OHCHR); see also S/2020/327. S/2020/401, para. 11. Briefing by the spokesperson of the Foreign Ministry of the Russian Federation, 27 February.