on 21 september, isil released video appearing to show it was deploying armed drones to prevent the saa from expanding its positions on the east coast of deir ez-zor. isis opened fire on the syrian army, but the army did not report any losses. 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. the 4th mechanized division and the 5th legion began an advance south of mazloum towards khasham.