A shocking video posted online Tuesday appears to show ISIS using a young child soldier to execute two alleged Russian spies in Syria.

The slickly-produced video - which bears all the hallmarks of previous ISIS propaganda productions - shows two men being interrogated in Russian about their alleged attempt to infiltrate the jihadi group on behalf of Russia's FSB spy agency.

In the forced confession one of the men, a Kazakh national, says he was ordered to gather intelligence on a particular ISIS leader and use a flash drive to steal sensitive information to pass on to the FSB. The other alleged spy confesses to having been sent to assassinate a senior ISIS commander.

Although it is unclear whether their confessions were genuine or not (the confessions were clearly made under duress), the video itself does appear to be authentic - as does its grisly end.

After extracting the confessions a burly ISIS fighter previously hidden off-screen appears in the video's final "scene", standing in a field behind the two kneeling suspects and delivering a speech against "disbelievers," a Kalashnikov assault rifle slung across his shoulder. Standing next to him is a young boy with shoulder-length hair, apparently from the Caucuses. The boy, who is no more than nine or ten years old, casually brandishes a pistol.

The young child calmly holds a pistol in his hand
The young child calmly holds a pistol in his hand

After quoting from the Koran, the adult terrorist adds in Russian: "Allah has gifted the Islamic State's security agency with the apprehension of these two spies... By Allah's grace, they are now in the custody of the lion cubs of the Caliphate."

At that point the young boy is gently nudged forward, pistol in hand, and calmly shoots the two men repeatedly in the head.

The "lion cubs of the Caliphate" is a name given by ISIS to it's child soldiers, which the Islamist terror group regularly shows off in a bid to encourage Muslim parents to indoctrinate their children to become "mujahideen", or "holy warriors".

Indeed, the video ends with a scene from a previous ISIS propaganda video released in November, showcasing a training camp for "the next generation" of jihadis. The same young boy features prominently in that video, telling the camera of his ambitions to grow up to "kill infidels" and identifying himself as "Abdullah" from Kazakhstan.

A recent study by the Middle East Media Research Institute (MEMRI) revealed the growing use of children by ISIS both in its propaganda and in military roles, but this is the first such graphic use of a young child in a public execution.