The Islamic State (ISIS/ISIL) is indoctrinating thousands of young boys it abducted in Iraq and Syria into becoming the next generation of jihadi killers, reports German news magazine Der Spiegel.

In a new report, the Washington Institute for Near East Policy also highlights the unprecedented system the Islamic State, also known as IS, is using to methodically brainwash children by exposing them to its Islamic extremist ideology.

The institute reports:

Stating that the Islamic State promotes religious extremism is far from sufficient in understanding what it seeks to achieve, much less what it teaches its students…

The report added that ISIS is creating a “fighter generation committed to IS’ cause…” in a way that is “both specific and unprecedented.”

Der Spiegel spoke to two young teenage Yazidi brothers who experienced ISIS’ indoctrination system first hand after they were kidnapped by the jihadist organization for nine months and imprisoned in its stronghold of Mosul in Iraq.

“They gave us drugs, and we believed everything after that,” they said.

Der Spiegel points out:

On one occasion, a militant beheaded a Yazidi before their eyes. ‘We will kill you, too, unless you convert,’ the men told them…

The recruitment of children takes place in several phases, beginning with harmless socialization. Islamic State hosts events in which children are given sweets and little boys are allowed to hold an IS flag. Then they are shown videos filled with violence. Later, in the free schools IS uses to promote the movement, they learn Islamic knowledge and practice counting and arithmetic with books that use depictions of tanks. They practice beheading with blond dolls dressed in orange jumpsuits. With a new app developed by IS, they learn to sing songs that call upon people to engage in jihad.

In areas controlled by IS, there is no alternative to these schools. They are collection points for children that IS selects for its military camps. Scouts visit the classes and determine which pupils will become ‘lion cubs.’

The two boys who spoke to Der Spiegel were identified only as Amir and Ahmed, ages15 and 16, from the Yazidi minority community in northern Iraq’s Nineveh province, home to several ethno-religious minorities.

Dier Spiegel reports:

There the terrorist organization used beatings and weapons to train them to become child soldiers, or ‘lion cubs of the caliphate,’ as IS puts it. The ‘lion cubs’ blow themselves up to kill supposed infidels. They witness beheadings, to learn how they are done. They donate blood for injured adult fighters. And they turn in traitors.

It is difficult to determine how many child soldiers Islamic State is training. Experts estimate that about 1,500 boys are serving the terrorist group in Iraq and Syria. Some are born to the militants. In fact, more than 31,000 women are currently pregnant in IS-held territory. Other children arrive with their parents from abroad when the parents join the jihadist movement. In many cases, the ‘lion cubs’ are also children of local fighters or orphans who join IS voluntarily. Others, like Ahmed and Amir, are kidnapped.

ISIS reportedly divided their young captives into two groups — weak and strong.

The German news outlet notes:

In the mornings before sunrise, Ahmed and Amir prayed. Then they learned the basic skills of a child soldier: How do you disassemble a Kalashnikov? How do you set an improvised explosive device? How do you detonate an explosive vest? IS men beat them with sticks and kicked them in the stomach — to make them tougher, as the men put it. In the evenings, the brothers laid on mattresses filled with fleas. Their bodies felt dead, they say. Their thoughts revolved around their mother and father, who they had last seen waving to them as they were taken away on an IS truck.