The collapse of Islamic State's "caliphate" in Syria and Iraq has been one of the most positive developments of recent years. Having terrorised the 10 million people it ruled over and used that territory as a base to develop and export its apocalyptic vision, the movement has been all but routed on the ground. Ultimately, it could not resist the combined firepower of the US-backed Kurdish-Arab forces, western air strikes and a revived Syrian military supported from 2015 onwards by Russian forces.
Yet the territorial defeat of Islamic State, also known as Isis, risks giving way to a dangerous complacency on two fronts. The first relates to the jihadist movement itself, which will continue to pose a threat long into the future. While Islamic State suffered heavy casualties – the United States estimates that about 50,000 of the group's fighters were killed – thousands of others are thought to have fled. Many of these fighters will have moved into hiding elsewhere in Syria, from where they can join the insurgency that Islamic State may well morph into. Some may defect to Al-Qaeda's branch in Syria or make their way through Turkey and on to Europe, where the authorities are already braced for an elevated threat of attack from trained returnees.
While Islamic State's self-image was closely bound up with its territorial acquisition, its potency as an idea was even more extensive. Across the Middle East and north Africa, self-declared affiliates have adopted its flag, mimic its methodologies and pursue the same brand of extreme violence. While some of these franchises, such are those in Algeria, Tunisia and Libya, are small or in retreat, others pose significant threats. Islamic State emerged in Afghanistan in 2015, and within a year it claimed more than 7,000 fighters and supporters and had a presence in most of the country's provinces. In the Sinai, local jihadists who pledged allegiance to Islamic State in 2014 have carried out hundreds of attacks.
The second area in which complacency must be avoided is in Syria itself. The rout of Islamic State has created a mistaken assumption that the war there is winding down. In fact the Syrian conflict was always a series of distinct, sometimes overlapping wars involving assorted regional powers and their proxies. Those wars continue to be fought with as much ferocity as ever. Turkey is stepping up its assault on Kurds in the north. A humanitarian disaster unfolds in Idlib, where the Syrian military is closing in on rebel strongholds. In Eastern Ghouta, a cluster of working-class suburbs of Damascus, 400,000 people remain besieged by Syrian forces, unable to access food or water. In the background, the risk of direct military confrontation between major powers on the ground is ever-present. That could make the battle to run Islamic State out of the desert seem a mere footnote in the story of the Syrian conflict.