Thousands of Isis fighters have already returned to their home countries amid confusion over the number of foreign jihadis remaining in the dwindling caliphate.
Research by The Soufan Centre estimated that at least 425 British Isis members have so far returned to the UK – the largest cohort in Europe.
But there are fears many have “disappeared” from the view of security services, who will not publicly confirm how many returnees have been jailed or are being tracked.
Out of countries for which data was available, only Turkey (900), Tunisia (800) and Saudi Arabia (760) had larger numbers of returning foreign fighters, according to the study.
Of the 850 people known to have travelled to warzones in Syria and Iraq from the UK, around 100 are women and 50 are children.
Interpol has already collected the names of around 19,000 people confirmed to have joined Isis, partly using the group’s own registration documents.
Many foreigners have left the battlefield.
In July 2017, the Radicalization Awareness Network (RAN) estimated that about 30% of the approximately 5,000 residents of the European Union thought to have gone to Syria and Iraq had returned home.
In some cases, for example in Denmark, Sweden and the United Kingdom, the number was closer to half. Earlier that year, in February, President Putin said that 10% of the 9,000 foreign fighters from Russia and former republics of the Soviet Union had returned.
Other countries, for example in South East Asia, have not only seen an influx of returnees, but also a certain number of foreign fighters who appear to have chosen to go there rather
than return to their own homes, whether or not advised to do so by IS leaders.
As of mid-June 2017, the Turkish authorities, having persuaded other States to help them monitor the increasing flow of foreigners passing through Turkey to Syria, had recorded the names of 53,781 individuals from 146 countries whose State of residence feared they might attempt to join the fight in Syria and Iraq.
The bases on which States have added names to the Turkish list vary, but the numbers
give some indication of how governments regard the strength of the IS appeal.
When combined with official figures of foreigners who have actually reached the conflict area, the scale of the challenge faced by Security and Law Enforcement Agencies charged with countering the threat from terrorism becomes apparent.
The emphasis of IS leaders has always been more obviously on building and defending the
caliphate than following the al-Qaeda example of focusing on the ‘far enemy’.
Its official slogan is “remaining and expanding”, but the concept of ‘expansion’ has moved from accepting the allegiance of new provinces, to the creation of new theatres of action.
Europe has seen several, attacks with many more thwarted. For example, France foiled
twelve attacks between January and September 2017; in a nine-week period between
April and June 2017, the United Kingdom saw three successful and five foiled plots;
Germany suffered five attacks in 2016, and has seen more since then.
In the United States, over 250 Americans have either tried to travel abroad or have succeeded in traveling to IS territory to fight within its ranks.
Of the 129 who have left the United States, 7 have returned from IS territory. Overall, the United States has charged 135 individuals for terrorism offenses relating to IS, with 77 convicted by August 2017.
Elsewhere, the threat of IS-inspired domestic terrorism has also persisted.
Turkey has been particularly hard hit, with 14 attacks up to July 2017, with a further 22 terrorist attacks prevented in 2016.
Australia suffered four and disrupted 11 Islamist extremist plots in the three years to August 2017.
Authorities in the Arabian Peninsula reported disrupting over 30 plots up to mid 2017; and in 2016 alone, there were seven IS attacks in South East Asia, with Malaysia reporting having disrupted a total of fourteen.
In addition, IS has also shown itself capable of attacks in Afghanistan, Bangladesh, Belgium, Canada, Egypt, Indonesia, Iran, Jordan, Kenya, Libya, Pakistan, the Philippines, Russia, Somalia, Sweden and Yemen.128 Some have involved returnees from Syria and Iraq.
Public reaction to incidents of domestic terrorism carried out by people known to the
authorities has been critical.
The public asks why, if these people were known to the authorities, were they allowed to be free, or not subject to round-the-clock surveillance.
This illustrates the fundamental problem — and success — of modern terrorism: governments are under pressure to limit freedoms on suspicion that a crime might be committed, rather than as a result of proven criminal activity.
They are under pressure to increase protective measures even though by doing so they are just as likely to raise public anxiety as to spread reassurance.
Given the numbers involved, the real problem for the authorities is in prioritizing targets,
and in establishing what sort of approach to take in each case. When a ‘known wolf’,
meaning a terrorism suspect, is able to carry out an attack, it is not necessarily because
the authorities are paying no attention; it is more likely because they have decided that
their attention should be focused elsewhere. Allocating more resources to security is not
always the answer; the focus has to be on reducing the threat to manageable levels rather
than increasing the capacity of the State to surveil its citizens, a policy that in any case
may be more likely to increase terrorism than to reduce it.
Government policies for dealing with returnees have generally fallen into one of two categories.
The first is incarceration, and many governments have criminalized going
abroad to join groups such as IS.
But proof is often hard to come by; and incarceration only postpones the problem, and at the same time risks further radicalization, or the radicalization of fellow inmates. 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.
At the same time, if extremists are grouped together, their views are likely to harden and
they will form close bonds.
The second approach is generally described as rehabilitation and reintegration, though
most returnees were never integrated in the first place.
Such programs are notoriously hard to design and run, and the majority of early efforts have stuttered or come to a halt.
Even recent attempts, such as in France in 2017, have failed.
These programs can be extremely resource intensive, and also risk criticism that they treat terrorists far better than other, less dangerous criminals, especially if conducted outside prisons.
There are indeed many similarities between the drivers that lead people towards violent
extremist groups and the drivers that lead them towards more traditional criminal
Dealing with child returnees is harder still.
But useful studies on treating both adults and children have emerged, and as practical experience follows, it may become easier to design programs and follow-up mechanisms that prove generally successful in understanding and limiting the threat from the wide range of different people that should be subjected to them. Institutional coherence, a culture of sharing information, and effective monitoring and evaluation systems will be essential to government efforts.
And increasingly, communities are likely to be involved, though with government support.
This whole of society response reflects the whole of society challenge that IS terrorism
has successfully created.
It has managed to shake the concepts of immutable borders and national sovereignty on which the international order is founded in a more dramatic and successful way than any preceding insurgent or separatist group.
The questions of identity, and the widespread mistrust of government institutions and mainstream politics that IS has managed to exploit are unlikely to go away; nor therefore is the phenomenon of foreign fighters and returnees, whether they join the remnants of IS or other new groups that emerge in its image.