In mid-November 2013, the Syrian military, backed up by Hezbollah, launched an offensive against the rebel-held Qalamoun Mountains in an attempt to cut rebel supply lines to Damascus from Lebanon.
[1] On 14 June, a rebel commander claimed that 29 Hezbollah fighters were killed (11 by an ambush) in and around Rankous over a period of two days.
[26] On 22 June, government forces launched an assault on the foothills of the Qalamoun mountains and state TV claimed the troops had captured some hills overlooking the Rankous plain and cut the route used by rebels to periodically return to the region.
[31] The Syrian army unleashed rocket salvos on rebel pockets as warplanes provided aerial cover for Hezbollah fighters working to cut off supply routes from Arsal.
[34] A security source confirmed more than 100 people had been killed since the start of the Hezbollah operation, including an aid to the rebel spokesman of the Abdullah Azzam Brigades.
[2] During the night between 1 and 2 August,[38] government troops, backed up by Hezbollah militiamen, ambushed rebel forces near the town of al-Jobeh, around 10 km from the border.
[43] On 4 August, the military had advanced and captured[12] the technical institute building, which was seized by the militants the previous day,[44] as the town came under heavy shell fire from multiple directions.
[16] During the day's fighting, the ISIS commander for the Arsal area was reportedly killed,[4] while al-Nusra forces retreated from the town.
[41] By 7 August, ISIS forces had also retreated from the town and a fragile truce was established and redeployed along the border with Syria.
[49] Two days later, the Lebanese Army entered Arsal in full force and re-established control over checkpoints that the militants had previously seized.
[51] After the offensive, the Al-Nusra Front and the Islamic State of Iraq and the Levant maintained a foothold in the region's rugged terrain.
[52] In late January 2015, ISIS announced its intention to further reinforce its positions in the Qalamoun region, in order to gain a launch pad for future operations in Lebanon.
[54][55] By 3 April, the Syrian military had advanced on three axes towards Zabadani, securing the western and eastern approaches to the city, and relatively paralyzing the defending rebels.
[59] In early May, al-Nusra Front and allied Islamists launched a preemptive attack against SAA and Hezbollah forces, capturing several positions.
[61] A few days later, the Syrian Army and Hezbollah seized control of a number of hilltops overlooking Assal al-Ward, reportedly killing dozens of rebels.
[62] At the same time, Hezbollah reportedly decided following an in-depth military assessment study to cancel their long-awaited offensive in the region after determining there was no need for a costly assault and instead to focus on cutting off all access ISIS and the al-Nusra Front might have to any Lebanese or Syrian towns.