Deir ez-Zor is the seventh largest city in Syria located to the northeast from the country's capital of Damascus, which had repeatedly became a place to armed clashes between Syrian forces and terrorist militias.
US warplanes hit Syrian government troops near the eastern city of Deir ez-Zor on September 17, leaving over 80 people killed. The Pentagon said initially that the airstrike was a mistake and targeted Daesh militants, while a number of Syrian officials stated that the attack was intentional.
Following the strike, Daesh terrorists launched a massive offensive in the area, however, the Syrian army managed to repell the attack.
Deir ez-Zor, which is still held by Syrian government forces, has been under siege of Daesh since July 2014.