WASHINGTON -- A U.S.-based security research firm says Russia, and the former Soviet region more broadly, is the single largest source for foreign militants fighting in Syria and Iraq.
The report, released on October 24 by the Soufan Group, documented the shifting makeup of fighters who have joined the Islamic State extremist group in the region, or some of the smaller allied groups.
More than 40,000 foreigners from more than 110 countries are estimated to have traveled to the region to join Islamic State (IS) fighters after they declared a caliphate in June 2014.
Two years ago, the Soufan Group estimated that Tunisia and Saudi Arabia were the largest sources of fighters in Syria and Iraq, followed by Russia.
Now, the group says, more than 8,700 from the former Soviet Union have traveled to the region, and an estimated 3,417 from Russia alone, primarily from the troubled North Caucasus, where Chechnya is located.
The new report shows how much that has shifted, as IS militants’ hold on territory has shrunken amid ongoing campaigns, with Russian and Syria leading one effort, and a U.S.-led coalition, with Syrian Arab and Kurdish fighters leading another.
Earlier this month, U.S.-backed forces said they had taken control of the IS stronghold of Raqqa, in Syria.
The shrinking battlefield has added to growing worries about what foreign fighters will do after, and whether some will return to their home countries to stoke insurgencies or terrorist activities there.
The Soufan Group said at least 5,600 people from 33 countries have returned home after spending time in Islamic State territories. Among Russian nationals, 400 have returned home.
Islamic State has its own affiliate in Russia's Northern Caucasus, and has claimed responsibility for more than a dozen killings of security forces in recent years.
Saudi Arabia has seen the highest number of its fighters -- 760 -- return home, the group said.