5,600 return to home countries from Islamic State-held lands, report says
At least 5,600 people from 33 countries have returned home after spending time in territory controlled by the Islamic State group in Syria and Iraq, according to a security consultancy.
The Soufan Group said the potential return of unknown numbers of foreign fighters represents a huge challenge for law enforcement agencies.
The New York-based group, which closely follows militant factions, said the extent to which displaced fighters will "wish to regroup, resurge, recruit and recreate what they have lost is as yet unknown".
It said more than 40,000 foreigners flocked to join IS from more than 110 countries before and after the extremists declared a caliphate in June 2014.
It said they included 5,718 from western Europe, more than 8,700 from the former Soviet Union and 439 from North America.
Thousands of IS fighters have been killed on the battlefield as Syrian and Iraqi forces have retaken nearly all the territory once held by the group, and many of those returning could be disenchanted with extremism, but the Soufan Group said it is inevitable that some will want to continue waging violent jihad.
It said IS fighters have already joined militant groups in the Philippines, Egypt's Sinai Peninsula, Afghanistan and Libya.
Meanwhile, Russia's defence minister said less than 5% of Syria remains under control of IS.
At its height the militant group controlled about half of the territory in Syria before its downfall began.
Speaking at a conference in the Philippines, Sergei Shoigu said "terrorists" controlled more than 70% of the country before Moscow launched its air operation at the end of 2015 to support President Bashar Assad's offensive against IS militants and opposition forces.