by ISIS to travel back and forth from the island to the mainland. A small network of tunnels was also discovered. ISIS suffered more casualties on 20 November after the 104th Brigade attacked their supply bases, sniper hideouts and repelled infiltration attempts. At least 33 militants were killed and 15 captured. ISIS positions in the Central Park on Sakr Island were further weakened. On 28 November, according to the Army, its units carried out raids against ISIS positions in the Central Park on Sakr Island. It claimed that at least 17 ISIS fighters were killed and 24 were arrested throughout the city. December 2014 ISIS offensive On 3 December, ISIS launched an offensive in the direction of the Deir Ezzor military airbase. They reportedly managed to capture the al-Masemekeh Building after a suicide bomber detonated a car near it. The next day, ISIS reportedly advanced further and captured Al Mari'iyah village and also captured parts of the al-Jafra village, On 5 December, ISIS captured the al-Jafra village. On 5 December, the Army launched a counter-attack and recaptured parts of Al Mari'iyah village and regained control of perimeter the Deir ez-Zor airbase from ISIS. The Army claimed that it had killed over one hundred ISIS militants since the start of the ISIS offensive. According to the SOHR, ISIS managed to capture some positions and military equipment on the mountain overlooking the city. During the night of 6 December, ISIS took control over the missiles battalion to the northeast of the airport and tried to storm the airbase itself, but failed. ISIS also pulled back from the heights overlooking Deir ez-Zor after it was exposed to heavy aerial bombardment, which reportedly used chlorine. Since the start of the offensive, fifty-one soldiers and sixty-eight ISIS militants were killed. See also Battle of Aleppo (2012–2016) Battle of Deir ez-Zor (1941) Siege of Deir ez-Zor (1915) References Deir ez-Zor Military operations of the Syrian civil war in 2011 Military operations of the Syrian civil war in 2012 Military operations of the Syrian civil war in 2013 Military operations of the Syrian civil war in 2014 Military operations of the Syrian civil war involving the Islamic State of Iraq and the Levant Military operations of the Syrian civil war involving the Syrian government Military operations of the Syrian civil war involving the al-Nusra Front Military operations of the Syrian civil war involving the Free Syrian Army