The boy in that photo was 12 years old.
The U.S.-armed and supported "moderate" rebels that chopped his head off just minutes after the photo was taken announced that cutting off the boy's head was an "individual error".
An "error".
You know? Like "Oops! I spilled something."

The Jerusalem brigade posted a statement on its official Facebook page on Wednesday, identifying the boy as 12-year-old Abdullah Issa, who they said was not a fighter.
"He lived in al-Mashhad [Aleppo] with his family, among multiple poor families that live in the area under the control of terrorists," read the statement, adding that the boy was ill.
"By taking one glance at the child - the argument that he was a fighter is immediately disapproved," the group said.
In the video, one of the rebels shouts: "He sent us a child today, he no longer has men!" seemingly referring Assad.
"We will leave no one in Handarat," they added, referring to the city north of Aleppo where heavy fighting between rebels and government forces has been taking place.

By "no one" they include sick 12-year olds.
Now to be fair, the United States cut off funding of the Nour al-Din al-Zinki Movement a few months ago. So your tax dollars no longer go to fund these child-killing "moderate rebels" fighting the Assad regime.
According to Wikipedia, the CIA funded them via the Turkey-based Military Operation Centre in 2014-2015.

The real kicker to this story is the official Obama Administration response.

"If we can prove that this was indeed what happened and this group was involved in it, I think it would certainly give us pause," State Department Spokesman Mark Toner told reporters, after being asked whether this incident would affect US assistance to this specific group.

"Give us pause"? Now there's a bold moral stand if I've ever heard one!
Next comes the drafting of a strongly-worded memo. Be sure to include the term "a few bad apples".

And speaking of investigating the slaughter of Syrian children, we've got another one to look into.

US airstrikes on a Syrian village have killed at least 73 civilians, a majority of them women and children, activists say, in the deadliest coalition attack on non-combatants since the start of the bombing campaign against the Islamic State...
In the early hours of Tuesday morning, activists described coalition aircraft hitting a cluster of houses in the village of Tokkhar, where nearly 200 people had gathered to seek shelter as the frontline shifted towards their homes. Most of those inside were killed or injured.
“The death toll is 117. We could document [the identity of] 73 civilians including 35 children and 20 women. The rest of the dead bodies are charred, or have been reduced to shreds,” said Adnan al-Housen, an activist from Manbij.

The good news is that it is likely the Administration will simply label the dead as "militants", like it normally does, and move on. That way Americans can continue to convince themselves that we are the good guys, while continuing to wonder why the terrorism problem keeps getting worse.

“This is likely the worst reported civilian toll of any coalition attack since the bombing campaign against Isis began nearly two years ago,” said AirWars director Chris Wood. The group had already warned of a rising civilian toll around Manbij.
“Since the siege began it’s our view that at least 190 civilians have been killed by coalition airstrikes, mostly US. We are concerned that the US-led alliance appears to have relaxed some of their rules concerning civilian casualties,” said Woods.