The Islamic State of Iraq and Al-Sham (ISIS) is not defeated despite the loss of the territory it claimed as its so-called ‘Caliphate’ in Iraq and Syria. It is stronger today than its predecessor Al Qaeda in Iraq (AQI) was in 2011, when the U.S. withdrew from Iraq. AQI had around 700-1000 fighters then. ISIS had as many as 30,000 fighters in Iraq and Syria in August 2018 according to a Defense Intelligence Agency estimate. ISIS built from the small remnant left in 2011 an army large enough to recapture Fallujah, Mosul, and other cities in Iraq and dominate much of eastern Syria in only three years. It will recover much faster and to a much more dangerous level from the far larger force it still has today.
The slow-motion reduction of ISIS’s territory and strength initiated by President Obama and continued by President Trump gave the group plenty of time to plan and prepare for the next phase of the war. It had a plan to recover ready before the “caliphate” fell and has been executing it during the anti-ISIS campaign conducted by the Iraqi Security Forces (ISF), the Syrian Democratic Forces (SDF), and the U.S.-Led Anti-ISIS Coalition. ISIS deliberately withdrew and relocated many of its fighters and their families from Mosul, Raqqa, and other important cities into new and old support zones in Iraq and Syria. ISIS’s forces are now dispersed across both countries and are waging a capable insurgency. ISIS retained a global finance network that funded its transition back to an insurgency and managed to preserve sufficient weapons and other supplies in tunnel systems and other support zones in order to equip its regenerated insurgent force.
ISIS began reconstituting key capabilities in late 2018 that will enable it to wage an even more aggressive insurgency in coming months. ISIS leader Abu Bakr al-Baghdadi asserted greater operational control over his forces in Iraq and Syria in June 2018 and is reconstituting command-and-control structures. ISIS is also reconstituting its capability to detonate waves of Vehicle-Borne Improvised Explosive Devices (VBIEDs) across Iraq and Syria – the signature of its early campaigns leading up to the conquest of Fallujah and Mosul in 2014. It has already detonated VBIEDs in liberated cities including Mosul and Raqqa. ISIS also resumed standardized media releases in July 2018, indicating that it has rebuilt key media capabilities.
ISIS’s insurgency will grow because areas it has lost in Iraq and Syria are still neither stable nor secure. In Iraq, ISIS has systematically eliminated village leaders and civilians who cooperated with anti-ISIS forces. Its goal is to weaken resistance and to fuel the population’s distrust of the Government of Iraq. It has re-imposed taxes on local populations in its historical support zones, displacing civilians and de facto controlling small pockets of terrain in Iraq. In Syria, ISIS is waging a three-front insurgency against the U.S.-backed SDF, the regime of Syrian President Bashar al-Assad, and Al Qaeda’s Syrian affiliate Hay’at Tahrir al-Sham (HTS). Its campaign degrades governance structures and halts reconstruction efforts, contributing to the perpetuation of state failure and violence in the Syrian Civil War.
ISIS will seek to reestablish territorial control in Iraq and in Syria. It will likely succeed if the U.S. withdraws.