The Eastern Syria campaign of September–December 2017 was a large-scale military operation of the Syrian Army (SAA) and its allies against the Islamic State of Iraq and the Levant (ISIL) during the Syrian Civil War. Its goal was to clear the city of Deir ez-Zor of any remaining ISIL forces, capture ISIL's de facto capital of Mayadin, as well as seize the border town of Abu Kamal, which became one of ISIL's final urban strongholds by the latter stages of the campaign.