The fall of Raqqa, ISIS's last and most symbolic stronghold, to Syria last fall granted a moment of relief worldwide and to the forces that had spent years doggedly eradicating the extremist group from the region. ISIS's so-called caliphate—a physical manifestation of its jihadist tenets—had finally been vanquished, and many thousands of its fighters had been killed or captured. Those who were left retreated to pockets of Syria.
But along with the tactical victory came the threat that national security experts had been warning of for years: the return of foreign fighters—and their extremist beliefs and training—to their countries of origin. Some 38,000 foreigners from 120 countries traveled to Iraq and Syria during ISIS's reign to aid the group in achieving its goal of building a caliphate. An estimated 7,000 of those foreign terrorist fighters (FTFs) died on the battlefield, and almost 15,000 left the conflict zones. Of those who left, about a third have been imprisoned and almost half—more than 6,800 people—have returned home without entering the criminal justice system.
"The fate and location of a sizeable proportion of FTFs appears to be uncertain," notes a March United Nations (UN) report on returning fighters. "Identifying and locating these remaining FTFs remains a critical priority for the international community."
Another challenge is determining whether returnees are defectors from ISIS, are merely supporters who have nowhere to go, or were sent home to continue their work.
While foreign fighters have not returned to their countries of origin in large numbers, as expected, they continue to trickle in—travelers turning up at an embassy in Turkey claiming they have lost their passport and wishing to return home, or a young family with expertly forged documents that allowed them back into a country that might otherwise turn them away.
Countries must figure out how to address such situations, and the approaches taken vary considerably. The process so far has been strewn with pitfalls, from an inability to prosecute foreign fighters over a lack of evidence to differentiating between ISIS defectors and jihadists to reintegrating children that were brought to the war zone or were born there. Several wide-ranging studies are looking at the makeup of the foreign fighters and the challenges countries may face in accepting them back into their borders.
While there have been many waves of foreign fighters for different causes over the years, the current group of ISIS foreign fighters is larger, more global, and more diverse in terms of age, gender, and experience in conflict zones, according to the UN report. They are also "the most operationally experienced, lethally skilled, and highly networked group of FTFs to date," the report notes.
The actual threat of these returning fighters has not yet been realized, but the UN report notes that foreign fighters have been involved in European terrorist attacks from 2014 to 2017.
"Although only 18 percent of attackers were known FTFs, the attacks they carried out were among the most lethal," the report states. "Most foreign fighters do not prove a threat on return, but those who do are highly dangerous and have been involved in a substantial proportion of the domestic plots in the West."
Another report written by the nonprofit research organization Soufan Center acknowledges that there is a range of returnees, from those who were only briefly with ISIS and came home after realizing it was not what they expected to those who were dispatched to return home and continue their efforts.
"These trained terrorists are not so much returnees as fighters dispatched to operate outside the caliphate," the report states. Due to the difference in threats these two groups cause, they should be dealt with differently.
Defectors should undergo close psychological and police assessment. "Terrorism is as much emotional as ideological, and even those who returned disillusioned or revolted by what they saw, or simply mentally or physically exhausted, may over time look back on the caliphate more positively and blame outsiders for its failures," the Soufan Center report says.
A study of returned fighters by psychologists for the Homeland Security Affairs Journal encourages countries to look carefully into the motivations and vulnerabilities of those who traveled to join ISIS.
"It will be incumbent on Western states to find adequate ways of determining who among returnees is a security risk at present, who may become one in the future, specifically by returning their allegiance to this violent group, and who can be safely reintegrated into society for the long term," the journal article states.
Resorting to imprisoning the worst offenders—if not all returning fighters—may seem like the best option, but it could make matters worse. Prisons are known to encourage and spread jihadist ideals. But, if managed well, prison can be a place for rehabilitation—which is especially important because those charged with terrorist offenses in the European Union spend an average of five years behind bars.
"Prison, or the threat of it, also appears to be a major stressor driving some back into the arms of ISIS," the journal article explains. "There is a tension in all societies between repressive measures against those involved in terrorism and rehabilitative measures that may put society at increased risk."
"Prison authorities are divided on the merits of segregating prisoners convicted of terrorism from the general prison population as the risk that an extremist prisoner will exert malign influence on his fellows, rather than become deradicalized through their influence, depends on too many variables to be easily calculated," the Soufan Center report finds. "At the same time, if extremists are grouped together, their views are likely to harden and they will form close bonds."
In its report, the UN reminds countries that a hardline response to returning foreign fighters may not be the most effective—especially since former jihadis will continue to return to their countries of origin for years to come.
"Returning and relocating FTFs are likely to remain a significant long-term challenge, requiring Member States to balance repressive and 'soft' responses," the UN report notes. "Many states have struggled to secure criminal convictions for FTFs, while imprisonment may delay, but not necessarily reduce, the threat they pose."
Britain. Home to notorious foreign fighters including teenage runaways and Jihadi John—a now-deceased member of the murderous quartet dubbed the ISIS Beatles—Britain is dealing with the aftermath of some 850 citizens who traveled to join ISIS. The capture of two members of the ISIS Beatles, who were responsible for the beheading of 27 foreigners, illustrates the challenges the country faces in prosecuting its citizens for involvement in ISIS.
The two Brits were captured by the United States-backed Syrian Democratic Forces (SDF) in January and remain held in Syria, where they have been continuously interrogated by U.S. forces under an agreement with the SDF. The United Kingdom stripped the men of their citizenship—an increasingly common practice in Britain—leaving them in legal limbo.
This is not an isolated scenario—the United States is urging countries to take responsibility for the hundreds of foreign fighters held by the SDF, but most do not want to repatriate citizens-turned-jihadi fighters.
Nobody has made moves to bring a case against the two men due to a lack of evidence needed to convict them of war crimes. The British jihadis mocked the situation in a recent interview with CNN, noting that accusations of their involvement in dozens of murders for ISIS were merely allegations. "I am not a democratic person, but I am being subjected to democratic law," one of the men said in the interview. "So it is only right for those who claim to uphold this to fully uphold it."
Canada. With about 180 Canadian foreign fighters in Syria and Iraq—including 60 that have already returned—Canada has implemented programs aimed at monitoring and deradicalization. Prime Minister Justin Trudeau has stated that returning fighters will be prosecuted where evidence exists, but rehabilitation should take priority so they do not pose a longer-term threat to the public.
The Canada Centre for Community Engagement and Prevention of Violence is tasked with countering radicalization and violence at an individual level, but focuses on research and does not directly interact with radicalized people. Quebec's Centre for the Prevention of Radicalization Leading to Violence has conducted 199 interventions of jihadist radicals—however, it has not yet worked with returnees.
France. France had one of the larger contingents of foreign fighters, with more than 1,000 citizens journeying to Iraq and Syria to join ISIS. An estimated 300 were killed and about 250 have returned to France, where they have either been imprisoned or placed on house arrest. France has determined that any ISIS fighters captured by the SDF will not be repatriated and should face justice in Syria.
France's criminal division recently released a report on jihadi women based on the court hearings of returning French women. Although jihadist ideology states that women cannot fight, some testified that they were given operational roles in ISIS that included recruiting, policing, and enforcing punishment.
"Although several French women were forced into joining the Islamic State by their husbands, most of the female recruits interviewed on their return to France expressed an attachment to the jihadist project," French newspaper Le Monde reports the memo as saying. The discovery has caused France to rethink its approach to returning female fighters, changing its policy to automatically arrest female returnees and monitor them more closely. Of the 72 women who have returned to France, 26 have been indicted, 15 have been arrested awaiting trial, and six have been tried.
Reintegration efforts in France are faltering, and the country's first center for deradicalization of young people closed due to a lack of use.
United States. With less than 100 citizens successfully traveling to Iraq and Syria to join ISIS, the United States is dealing with the return of 12 foreign fighters—nine of which have been arrested and charged with terrorism-related offenses, and three that have not yet faced criminal charges. Unlike many countries, the U.S. had an existing law against jihadist travel before the flood of foreign fighters journeyed to join ISIS. Under that law it has charged some 153 citizens who attempted to join ISIS or plotted ISIS-inspired schemes.
And a report by George Washington University's Program on Extremism notes that due to the difficulties of gathering evidence of a traveler's activities in Syria or Iraq that is admissible in a court of law, prosecutors often have to charge the returned fighters with lesser offenses.
"While the average prison sentence for individuals who attempted (but failed) to travel to Syria and Iraq is approximately 14 years, the seven successful travelers that have been convicted from 2011 to 2017 received an average sentence of 10 years in prison," the report states.
While deradicalization and reintegration resources have been reduced under U.S. President Donald Trump, the report notes that such programs will be necessary once the returned jihadists are released from prison. There are currently no deradicalization or rehabilitation programs for jihadist inmates in the U.S. federal prison system.
"Without these programs, incarcerated travelers have few incentives to renege on their beliefs and may attempt to build networks in prison or radicalize other prisoners," the report states.