Iraq and Syria have both declared victory over ISIS in recent weeks.
As US-backed and Russian-backed forces battle to retake the remaining pockets of ISIS-held terrain, Mattis said the US military’s longer-term objective would be to prevent the return of an “ISIS 2.0.”
History suggests the militants will respond to any discontent with brutality, especially after losing control of the cities of Falluja and Ramadi this year.
The leader of ISIS was reported to be among thousands of hardline militants still in the city, suggesting the group would go to great lengths to repel the coalition.
Prime Minister Binali Yildirim said that Turkey will never allow the formation of an artificial state in the north of Syria.
The government air strikes in Syria’s northeastern city of Hasaka mark the first time the Syrian military has deployed its warplanes against Kurdish groups during the war.