LONDON — There are roughly 5 million children living under the so-called Islamic State in Iraq and Syria. As such, it was only a matter of time before the worst terror group of our lifetime set its sights on them.

And now it has.

Working with Child Soldiers Initiative, and endorsed by UNICEF, my counter-extremism organization Quilliam has released a seminal report (PDF) documenting the use of child soldiers by ISIS. This report makes for cruel reading.

The United Nations has received credible but unverified reports suggesting that ISIS has created a youth wing called Fityan al-Islam, meaning boys of Islam. The precedent seems to have been set by the former Baathist regime of Saddam Hussain in Iraq, which in the late 1970s established the Futuwah (Youth Vanguard) movement with the most important Iraqi child soldier units known as Ashbal Saddam, or Saddam’s Lion Cubs.

Apparently after studying the Nazi regime, which created the Hitler Youth, ISIS is now busy training and indoctrinating children en masse. But as with most things ISIS lays its hands on, the group has taken its brutality involving children way beyond anything Hitler or Saddam ever did.

ISIS has abducted between 800 and 900 children ranging between the ages of 9 and 15 from various regions of Mosul city and province. From last August to February, 254 instances of children being used in ISIS propaganda were found. Many are being trained as spies, preachers, soldiers, executioners, and suicide bombers. In counting lessons children tally up guns or tanks instead of apples and oranges. Media outlets within the “caliphate” have issued statements warning that children who refuse to conform with ISIS orders will be flogged, tortured, or raped.

Of particular concern here in the U.K., there are as many as 50 British children subjected to direct ISIS command and control. To our collective horror, some of these have been forced to carry out beheadings or hold up decapitated heads to show they are ready to embrace the “jihad.” In the past six months alone ISIS propaganda has depicted no less than 12 child killers. One recent macabre video showed a 4-year-old British boy apparently detonating a car bomb, killing four alleged spies trapped in the vehicle.

The girls fair no better. While in captivity young women and girls have been taken and raped on a daily basis by ISIS fighters. Most girls are being processed to be molded as wives and mothers of future soldiers. As if shaping an unborn army, estimated 31,000 women living under ISIS rule are pregnant.

Teachers, too, are forced to enlist in this totalitarian social experiment. Four teachers were abducted from a high school in Mosul last January for opposing ISIS, and last March a primary school teacher was executed for criticizing the group.

But it gets worse.

Until now, if we want to make a comparison, the use of child soldiers in Liberia and Angola was restricted to abducting them from their families, and forcing them to fight. What makes ISIS’s use of children more insidious than Hitler’s, Saddam’s, and these African cases, is the active involvement of the families.

Parents have no choice but to comply with ISIS instructions to play a part in brutalizing their children. Mothers are given books by ISIS instructing them on how to raise their offspring for “jihad.” This includes telling bedtime stories about martyrdom, exposing children to graphic content through jihadist websites, and encouraging them to improve their child’s military skills and fitness. Using parents in this way is guaranteed to weaken any emotional resistance a child may naturally have to committing atrocities.

As ISIS knows well, Islamic heritage is no stranger to the power of youth, even in positions of authority. The Prophet’s cousin and son-in-law, Ali ibn abi Talib, was around 10 years old when he pronounced himself the first male to follow Muhammad. Ali went on to become the famed fourth Caliph of Islam.

The Prophet’s adopted grandson Usama ibn Zayd was reported to have been only 17 years old when he was sent by Muhammad to lead an army against Rome. It was also at 17 that the Islamic military commander Tariq ibn Ziyad is said by Muslims to have conquered Spain. We are taught that Muhammad ibn Qasim, too, was 17 when he won his decisive battles for Islam in the Indian subcontinent. Bakhtiyar Khalji is fabled to have been only 18 years old when he established Muslim rule in Bengal.

Perhaps most famous of them all, we speak of a 21-year-old Muhammad Al-Fateh who defeated the Byzantines and took Constantinople for Islam, as foretold by the Prophet: “Verily you shall conquer Constantinople. Blessed be the leader, and blessed be that army!”

In this way, the relationship between conquest and youth is certainly not alien to Islamic tradition. The Prophet even conferred upon it special status: “On the Day of Judgment when there is no shade except in the shadow of Allah’s throne, seven classes of people will find shade in Allah’s shadow.” The first group to be honored in this way were “those who rule justly,” and the second group is “youth who are raised worshipping Allah.”

Today we would consider such fabled warrior-rulers to be children. Muslims may tell these stories, but most wouldn’t even allow their own 16-year-olds to stay out beyond a nighttime curfew. We have come to insist that our youth abandon any delusions of grandeur and simply complete their education and get a job. Likewise, we have come to rightly reject military conquest as a means to spread any religion or culture. Medieval times were medieval times the world over. That was then, and now we have evolved beyond such a harsh world order.

Except in ISIS, medievalism is back. And as this group proactively fetishizes, and attempts to revive, the Middle Ages in all their gore and glory, the world is simply unprepared to deal with the moral paradoxes this raises.

ISIS knows our weakness. There is a joker in the deck that refuses to abide by any of our modern rules. For as footage surfaced of an ISIS orphanage in Iraq’s second-largest city, Mosul, being used as a drill site for the next generation of terrorists—a jihadist child army—the question I leave you with is this: What world leader could possibly authorize an airstrike on a training camp full of children?