On 27 August, as part of a wider campaign in central Syria against ISIL, the Syrian Arab Army, launched a major offensive against the city of Deir ez-Zor in an attempt to break the siege.

[15] On 18 September, pro-government forces crossed the Euphrates River[16] using makeshift bridges, and launched an offensive on the east bank of the city of Deir ez-Zor, advancing within 3 miles (5 km) of positions held by the SDF.

[18] On 20 September, the Russian Defense Ministry accused the US-backed SDF of assisting ISIL in East Deir Ez-Zor in various ways in an attempt to prevent the Syrian army and its paramilitaries from capturing the region.

[20] Meanwhile, the Syrian Arab Army (SAA) continued its march along the east coast of the Euphrates River, capturing a new town located near the strategic Al-'Omar's oil fields after fierce clashes with ISIS members.

With the support of heavy artillery from the 113th and 137th Brigades of the 17th Division, the 5th Legion of the Syrian Arab Army reported it had overcome the positions of the ISIS east of the recently captured al-Marat in order to advance to Mazloum.

[25] On 18 October, Major General Issam Zahreddine, the commander of 104th Airborne Brigade of the Republican Guard who lead the Syrian Army during the three-year siege of Deir ez-Zor, was killed by a land mine in Saqr Island within Euphrates river.

[26][27] Syrian Army captured southern parts of Deir ez-Zor industrial area, including paper factory and construction zone, north of village of Al-Salhiyah in the morning of 20 October.