A horrifying new video released online on Tuesday appears to show ISIS using a young boy to execute a pair of captives the terror group claims are Russian spies.

The slickly-produced video shows two men being interrogated in Russian about their alleged attempt to infiltrate ISIS. One captive, and alleged Kazakh national, states he was ordered to spy on an ISIS leader , while the other confesses to having been sent to assassinate a senior ISIS commander. The video later skips to an outdoor scene where the alleged spies are kneeling in a field before a burly man and a young boy of 10 or less armed with a pistol. 

"Allah has gifted the Islamic State's security agency with the apprehension of these two spies," the adult states. "By Allah's grace, they are now in the custody of the lion cubs of the Caliphate."

At that point the young boy steps forward and appears to calmly shoot the two men repeatedly in the head.

ISIS has been known to employ child soldiers, which it calls the "lion cubs of the Caliphate." The video ends with a scene from a previous ISIS propaganda video released in November, showing a training camp for "the next generation" of jihadis. The same boy appears in that video, speaking of his ambitions to grow up to "kill infidels" and identifying himself as "Abdullah" from Kazakhstan.

More On This...

The U.S. State Department did not immediately return a request for comment about the video. An official with Russia's Federal Security Service declined to comment when asked about the video by Russia media outlet RIA Novosti. The news agency said the Russian embassy in Damascus also had no comment.

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.