DAMASCUS — “Islamic State” recruited at least 400 children in Syria in the past three months and given these so-called “Cubs of the Caliphate” military training and hardline indoctrination, a monitoring group said on Tuesday.

The Syrian Observatory for Human Rights said the children, all aged under 18, were recruited near schools, mosques and in public areas where ISIS carries out killings and brutal punishments on local people.

One such young boy appeared in a video early this month, shooting dead an Israeli Arab accused by ISIS of being as spy. A French police source said the boy might be the half-brother of Mohamed Merah, who killed three soldiers, a rabbi and three Jewish children in Toulouse in 2012.

“They use children because it is easy to brainwash them. They can build these children into what they want, they stop them from going to school and send them to IS schools instead,” said Rami Abdulrahman, head of the British-based Observatory.