In 2014, the Islamic State (ISIS) seized Mosul and later announced the establishment of a caliphate. While counterterrorism efforts initially focused on the group’s centers in Mosul and Raqqa, it is the areas adjacent to the Iraq-Syria borders that would prove to be the group’s last stand after major defeats. Eastern Syria had served as a point of strategic depth when ISIS arose in the aftermath of the fall of the Saddam regime. The area served as springboard for the group’s resurgence in the late 2000s and early 2010s, and in 2013-14 it allowed for the group to render Iraq and Syria into a singular battlespace.
Today, this cross-border frontier offers ISIS the ecosystem it needs to survive and restore its capabilities. Any strategy to achieve the enduring defeat of ISIS must focus on sanctuary denial on both sides of the Syria-Iraq border and address factors including social cohesion, economic opportunity, security, and trust in government. While there is currently no regime likely to do this in Syria, there are tangible steps Iraqi authorities can take to undermine the group’s support base and enablers in the area.