As the Caliphate in Iraq and Syria crumbles, European governments are paying particular attention to foreign fighters returning to their countries of origin. What to do with children returning alongside them, however, has received much less focus.

The precise number of children who will make it to Europe from the Islamic State’s heartland is unclear. While some of these children were taken forcibly to Syria and Iraq and already have European passports, others were born there to at least one European parent. Proving their nationality may not be straightforward. Identification papers may be lost or only ever have been issued by the Islamic State (and therefore not recognized by nation states). Some parents will have been killed in the fighting, and the paternity of children of rape victims unclear.

However, governments are at least somewhat cognizant of the scale of the problem. By the end of 2016, for example, the Netherlands was aware of over 40 children taken to ISIS-occupied territory by their parents, and the total number of children with some kind of connection to the country is around 80. In France, the number is higher: approximately 460 children in ISIS-controlled territory, with a third born there. Seemingly, there are American and British children also still in the Caliphate.

The Islamic State has undoubtedly exposed these children to their ideology. Europol’s EU Terrorism Situation and Trend Report warned this year that “IS propaganda has repeatedly depicted the training and indoctrination of minors.” A 2016 report from the British counter-extremism think tank Quilliam outlined how “[b]oys learn a rigid Islamic State curriculum” and children “attend ‘Jihadist Training’, which includes shooting, weaponry and martial arts.” Daniel Koehler of the German Institute on Radicalization and De-radicalization Studies has commented, “[t]hese children are … being told you will burn, you will be tortured if you do not do this—if you do not kill this infidel, you will end up in hell, your mother will end up in hell.” This helps explain why multiple videos have emerged of children brutally executing detainees in ISIS-controlled areas and why researchers at Georgia State University were able to demonstrate that ISIS has been able to deploy so many children in military operations in Iraq and Syria.

There is hardly an established playbook for how European democracies should integrate into society children potentially already radicalized. There are, however, options.

At times, prosecution will be appropriate. ISIS’ propaganda output shows that some of these children have committed murder, such as the 13-year-old Brit who executed a Kurdish captive. Yet country-by-country, the law treats very young children differently than teenagers. In Germany, for example, the age of criminal responsibility is 14 years old, whereas in Belgium, it is 12, and in the UK, it is 10. In some cases, when there is compelling evidence and domestic prosecutors consider it in the public interest, it will be appropriate to bring charges. Because of the age of responsibility, the 13-year-old British child could be prosecuted and sent to a juvenile prison, but the four-year-old Brit filmed blowing up a car containing four of ISIS’ prisoners last year could (and should) not. He could, however, be placed under a curfew or work with a government youth-offending team.

Another option is to allow the state to take children away from ISIS-sympathetic parents and place them into care. This will be necessary at times, though care in and of itself is not a guaranteed panacea: Ahmed Hassan, an 18-year-old Iraqi refugee who had lived with his British foster parents for the last 18 months after his parents were killed in Iraq, still carried out a bombing on the Tube in southwest London this September.

The case of Hassan also demonstrates that for the older child returnees, monitoring by security services will be appropriate. However, surveillance presents a significant resourcing challenge. Many intelligence agencies are already over-stretched, and it’s not clear when monitoring should end.

All these factors mean that there should be a role for de-radicalization initiatives.

This is something that is not just relevant to returnees; children are being radicalized in the West, too. Western teens and pre-teens have carried out dozens of plots. For example, in June 2016, French authorities arrested a 13-year-old in the suburbs of Paris who had pledged allegiance to Abu Bakr al-Baghdadi and was planning a knife attack on a civilian target. In November 2016, a 12-year-old German Iraqi attempted multiple bombings in Ludwigshafen, western Germany. The UK government has identified 2,127 children under the age of 15 as possible extremists.

So de-radicalization initiatives would be important even were it not for children arriving from the Caliphate. European governments have made uneven progress in establishing such programs, which are unarguably experimental and will not always succeed. Yet a process utilizing social workers, psychologists, youth-offender services and child protection agencies to try to reach these children is as good an option as exists. As French Minister for the Armed Forces Florence Parly recently said when discussing child returnees from the Caliphate, “the challenge for us is to turn them into citizens again.”

Demonstrating to children the dangers of radical Islamist ideology is not impossible. For example, the UK Home Office recently disclosed that a nine-year-old had stood up in class and pledged his support for ISIS. This led to his referral to Channel, the government’s de-radicalization scheme, and the child has since recanted those views.

One challenge is that Channel is voluntary. It requires consent from the parent or guardian of the child. As this could be the same parent that took them to Syria in the first place, that is an obvious problem. The UK government’s 2015 annual report examining CONTEST, its counter-terrorism strategy, stated it would be “introducing a new deradicalisation scheme, which will be mandatory where the law allows, for those who are further down the path to radicalisation and who need a particularly intensive type of support.” This idea has not been fleshed out more fully yet but should be—especially for cases involving children.

There may be reluctance at the notion of the state involving itself so heavily in the realm of ideas. Certainly, no option outlined here is desirable. Yet the most undesirable option is doing nothing. Such a course of action will only increase the likelihood that these child returnees will become the next generation of Islamist insurgents.