A Syrian rebel group once deemed "moderate" by the U.S. was captured on film beheading a child in Handarat, near Aleppo, in a gruesome video that circulated on social media on Tuesday.

The Daily Beast reports: "There are two clips from the unsavory events. One shows five militants surrounding the boy. In the second, one of them stands over him on the truck and cuts the boy's head off with a dull knife, raising it over his head."

In the video, the rebel group accused the boy of being a fighter for the Jerusalem Brigade, a Palestinian militia fighting alongside regime forces, Al Jazeera reports. The news outlet adds that the Jerusalem Brigade issued a statement shortly after the video's release identifying the boy as 12-year-old Abdullah Issah, saying he was not a fighter and condemning the grisly attack.

The group, Harakat Nour al-Din al-Zenki, was reportedly receiving funding and weapons from the CIA until at least December 2014 and using American weapons until 2015.

Critics of the Obama administration's approach to the Syrian conflict have long sounded the alarm about the dangers of arming and funding so-called "moderate" rebel factions in the war-torn country.

"Even if they no longer get U.S. aid, [the beheading] still shows the moral pitfalls of what we're trying to do in Syria," Daveed Gartenstein-Ross, a terrorism expert and senior fellow with the Foundation for Defense of Democracies, told the Daily Beast.

"Details conflict about which groups, exactly, comprise the 'moderate' Syrian rebels funded by the U.S.-led coalition," the Daily Beast adds, "but critics have long warned that fluid dynamics and shifting allegiances on the ground make it difficult to predict which groups will be aligned with U.S. interests."