The resurgence of ISIS remains a continuing regional
security concern twelve years after Mosul’s fall
Twelve years after ISIS captured Mosul in June 2014, the city’s fall is still regarded as one of the most significant turning points in the modern history of Iraq and the wider region. In a rapid offensive, several hundred militants overran Iraq’s second-largest city, seizing government institutions, military bases, and Mosul International Airport within hours. The group soon declared the establishment of its so-called “caliphate,” initiating years of widespread violence, mass killings, and systematic destruction.
The emergence of ISIS was rooted in a complex political and sectarian environment in Iraq at the time, marked by deep divisions and governance failures. These conditions contributed to instability that allowed the group to gain local support in some areas, while the Iraqi army—despite its size and equipment—collapsed in Mosul with little resistance, abandoning significant military assets.
Following the occupation, ISIS expanded its campaign of atrocities, including the genocide against the Yazidi community in 2014, which resulted in thousands of deaths, abductions, and mass displacement. Across Mosul and the Nineveh Plains, centuries of coexistence among diverse ethnic and religious communities were violently disrupted.
Although ISIS lost territorial control in Iraq in 2017 and in Syria in 2019, security analysts continue to warn of the persistence of extremist ideology and sleeper cells across the region. Instability in parts of Syria, including changes in control of detention sites and camps previously holding ISIS-affiliated individuals, has further increased concerns about possible regrouping and renewed activity.
Despite its territorial defeat, the group’s underlying networks and ideology have not been fully eliminated, and regional security experts continue to stress the need for sustained counterterrorism efforts to prevent any future resurgence.