Kasswara* joined ISIL when he was 14.
"We were the 'cleaners' group. Cleaning means slitting the throats of those who belong to the other side and are hiding," the teenager from Raqqa, Syria, said.
"A guy from my area was decapitated by [ISIL] because of me. People had their hands chopped off because of me."
Since the start of the Syrian civil war, armed groups have been using child soldiers in combat. ISIL, or the Islamic State of Iraq and the Levant group, is thought to have recruited around 2,000 children. They are called "ashbal al khilafa", the "lion cubs of the caliphate".
Kasswara, who is now 16, fled ISIL, also known as ISIS, after being sexually assaulted and is currently living in Greece. He tells his story in Witness: Lion cubs of ISIL.
Like Kasswara, a number of former cubs have fled to Europe where they live in anonymity. And with ISIL swiftly losing ground in Iraq and Syria, more child soldiers are bound to leave their ranks, raising concerns about whether they will pose a future danger.
Mia Bloom is a professor at Georgia State University who is writing a book on children in "terrorist" organisations.
Ishmael Beah fought as a teenager in the Sierra Leone civil war in the 1990s and is now an author and UNICEF advocate for children affected by war.
This is their take on what should happen with ISIL's former child soldiers.
Mia Bloom: A lot depends on the ways in which the children became involved. There's a whole range on the spectrum from luring to outright coercion.
Some children in orphanages and hospitals in Syria and Iraq were just taken. Some were handed over by the parents. Some joined ISIL as a way to ensure that their families would get to keep their house, and would get an allowance and food.
We know that ISIL used techniques to draw children in. They would have these events and give away free candy.
Or they would march the cubs down the street in brand new uniforms so that the other children would admire them and aspire to be like them. The organisation made membership of the cubs to be a rare and desirable thing.
The children of foreign fighters had a different sort of access. There were different schools for them whose language of instruction might be English or French.
Ishmael Beah: "I was not forced to become a child soldier as some of the other kids were.
The circumstances pushed me to go to a base of the Sierra Leonean army to enlist. I had lost my family, my home and everything I knew as a child.
The military was the safest place to go, to be protected from what was going on in the country.
In the army, there was no choice but to fight. If you didn't kill, you would get killed. You had to fight for ammunition, you had to fight for food. Killing became like breathing. You didn't even think about it.
If you just sit around all day and nothing is happening in your life, the war is more likely to haunt you
After more than two years, when I was nearly 16 years old, my lieutenant handed me over to UNICEF. At first, I wasn't happy at all. I had gotten accustomed to the war. The army had become my new family. It's all I knew and all I thought my life would be.
It took a while for that to change. I spent eight months at a re-integration centre. What made the difference is that the staff who worked at the centre looked at us just as children, not soldiers.
I was also given the opportunity to go to school and do something with myself. I discovered I had an intelligence that I could use for something else than war.
Eventually, I studied political science and did so many things I didn't think I was capable of doing. It fostered an environment where I could create new memories to compete with my trauma.
You can come from war, and you can recover, but if you just sit around all day and nothing is happening in your life, the war is more likely to haunt you.
The community was involved in our reintegration too. They had to learn to believe in us again. A former child soldier often creates the expectation that if you were once violent, you'll always be violent.
Bloom: There's always a risk of recidivism. This is true for adults and children. We did research in Pakistan into children who had been involved in the Taliban.
These children were brought to the educational level for their age. They were given vocational training so they could go on to have a job. And they were re-educated religiously because the Islam these kids had studied was completely corrupted.
There was also a lot of aftercare, where the communities embraced the children and brought them back in.
This approach was successful, and some of the children who had been involved with the Taliban became like normal children again. So there is a possibility of a happy ending.
Ostracisation might push them back over the edge
If members of the family were part of the Taliban, recidivism was much higher. This is where the ISIL situation becomes problematic, because in many cases the parents willingly gave the children over to the cubs.
This counts especially for the foreign fighters, so the ones who are going back to Germany or France.
These children also have a higher risk of relapsing because of the stigma attached to the group.
Even if your parents took you when you were four years old, even if you didn't necessarily sympathise with the group, back in a European city you will be perceived as a foreign element, and that's very dangerous. The ostracization might push them back over the edge.
Beah: One of the problems for us going back into our communities was that people knew we had been given opportunities that they didn't receive.
In the UNICEF centre, we had running water; most people didn't have running water. We had two meals a day; most people did not have that.
So a lot of people thought to themselves: If you fight in a war and you kill people, foreigners will come and give you all these opportunities.
At the re-integration centre, we were constantly being attacked by the community. People would throw stones at our building and come running into our compound to start a fight with sticks and stones.
It was clearly coming from a sense of injustice.
This is why I believe a holistic approach to healing society is necessary. The child that didn't fight was affected by the war too, so they should not be treated differently.
Bloom: Young ISIL fighters returning to Europe puts a huge onus on these countries. Keep in mind that many of these countries already have problems with their Muslim communities when it comes to giving them access to jobs, education and good healthcare.
Imagine how perverse it would be if people who didn't join ISIL don't have access to good programmes and returning fighters get all these resources thrown at them. You're going to have a very absurd situation.
Beah: I joined the army when I was 13. As a child, you don't just go to the battlefield, pick up a gun and shoot another human being. You have to be brainwashed to some extent to believe that what you are doing has some merit.
When I was in the army, I really believed I was fighting the right fight. My family had been killed, and I was fighting to make sure that people wouldn't do this to other children. It appealed to some of us who had lost everything. We wanted someone to pay for what had happened to us.
Now, after the war, I see that this narrative was used by all the groups that would recruit children and I no longer believe in it. But in order to function as a child in that madness, I had to believe in something. I had to justify what I was doing in order to survive.
Bloom: For some children who have fought for ISIL, we could make the argument that they're brainwashed, or they're parroting what the adults say. But for the ones who were 16 or 17 when they joined, it's much harder to convince me that's the case.
I make a distinction between the children who were exposed to violence and children who participated - the ones with blood on their hands. It's going to be a much more challenging experience to re-integrate them.
They're all children, and they all have to be treated as such. But we cannot be so blind as to assume that just because they're a child, they're innocent.
Beah: Until anybody can show me a war that children under 18 started all on their own, I don't think any former child soldiers should be prosecuted.
What I would tell the children coming out of ISIL is that it's going to be very difficult. There's a lot of stigma that they are going to have to deal with. They should make sure they have a strong support network to fall back on. It's not easy; it's going to take some time, but it is possible.
* Not his real name