Beginning in 2016, the Islamic State lost ground nearly as quickly as it had captured it.
In Iraq, security forces backed by the United States, and elsewhere Iranian-backed Shiite militias, ousted the group, retaking Mosul in mid-2017 and officially declaring the group defeated in the country by the end of the year.
American-backed, Kurdish-led forces regained territory in Syria, including Raqqa in October 2017. Along Syria’s eastern border, forces backed by the Assad government and Russia also took back territory. But many of the cities once held by the Islamic State are shells of their former selves. In Raqqa, two-thirds of the city was destroyed in the coalition fight against the group. In Mosul, centuries-old mosques and markets were reduced to rubble.
But even as territory has been wrested from the Islamic State, the group has continued to spread its ideology online and encouraged supporters to carry out attacks worldwide. While the state it once declared has largely disappeared, it remains a significant threat, experts say.