At first glance, the training camp appears no different from the many others shown in propaganda videos posted by al Qaeda's affiliate in Syria. Hooded recruits in camouflage shoot at targets or march in formation under the black flag of the Islamic State of Iraq and Syria.
But look closer and the "fighters" appear quite small. The tallest are barely chest-high to their instructors, and the shorter ones wear ill-fitting uniforms and appear to struggle under the weight of their weapons. A photo of the recruits without their hoods confirms that all of them are young boys.
They are "Zarqawi's Cubs," the youth brigade of Syria's most fearsome Islamist rebel group and one of the newest manifestations of al-Qaida's deepening roots in rebel-controlled sections of the country. Building on earlier efforts to expand their influence in Syrian schools, radical Islamists appear to be stepping up efforts to indoctrinate and train children, some as young as 10, according to independent experts who have studied the phenomenon.
The establishment of the Zarqawi's Cubs camp - revealed in a video posted last month by the Islamic State of Iraq and Syria, or ISIS - is viewed as particularly worrisome because of the similarities to Iraq's "Birds of Paradise." That brigade was created a decade ago by the same terrorist group, in its earlier incarnation as al Qaeda in Iraq, to train children for military missions, including suicide bombings.
"This is the future threat," said Steven Stalinsky, executive director of the Middle East Media Research Institute, a Washington nonprofit organisation that has tracked the exploitation of children by Syrian fighting groups over the past two years. "These are the children of al Qaeda."
UN agencies and human rights groups have accused multiple Syrian factions - including secularist rebels and pro-government militias - of recruiting children for military roles ranging from scouting to actual combat.
Researchers from Human Rights Watch interviewed boys as young as 14 who were used to transport weapons or serve as lookouts. Even younger children were put to work loading bullets into magazines for assault rifles, said Sarah Margon, acting director of the group's Washington office.
"It's something that children often do because their fingers are smaller," Margon said. But such practical considerations aside, "for those looking to indoctrinate, it is a ripe setting for indoctrination," she added.
The Obama administration last year imposed restrictions on some of its nonmilitary aid to Syria in part because of concerns about the use of child soldiers. Invoking a 2008 law forbidding assistance to countries that use child soldiers, the administration approved restrictions on certain types of nonmilitary aid to Syria as well as the Central African Republic, Burma, Sudan and six other countries, according to State Department documents.
The appearance of training camps for young boys suggests a more systematic effort to incorporate the youngest Syrians into the conflict, as ideological supporters and as combatants in a religious war against a regime led by the country's minority Alawites, members of an offshoot of the Shiite branch of Islam, according to experts who study jihadist groups.
Radical groups often post images on social media that highlight the role played by children, and some attempt to tailor their messages to appeal to the very young, said Aaron Zelin, an expert on jihadist groups at the Washington Institute for Near East Policy.
"They understand that they are the future and, therefore, need to be exposed and indoctrinated to the 'cause,' " Zelin said. It explains why some groups operate age-based training camps that start with "cubs" and progress to "lion scouts" for older teens and adults, he said.
The ISIS youth group was named in honour of Abu Musab al-Zarqawi, the Jordanian who founded al-Qaida in Iraq, a group notorious for its spectacular suicide bombings targeting Shiite mosques and bazaars in Iraq's Shiite neighbourhoods, as well as its videotaped beheadings of Western hostages. Zarqawi, killed in a US airstrike in 2006, remains an inspirational figure for Islamist extremists worldwide, as well as the ideological father of ISIS and other al-Qaida-allied rebel groups in Syria, including Jabhat al-Nusra.
The video depicting the Zarqawi's Cubs camp describes the location of the facility as near Ghouta, the same eastern suburb of Damascus that was struck in a chemical-weapons attack in August that killed more than 1,000 civilians. Much of the region has been held by rebels for months, despite intense fighting in some villages.
The boys are shown being led by masked instructors through small-arms exercises and sitting in groups under the ISIS banner, some of them weighed down by bandoleers of machine-gun ammunition. Other images show the boys undergoing instruction or, in one instance, talking happily over a lunch of flatbread. Beverages are distributed in colorful cups adorned with the cartoon "happy face."
In the soundtrack, Arab voices sing a mournful song. "Oh mother, don't be saddened by my leaving," it says at one point, explaining that the boys are going away to fight "for the sake of defeating the Jews."
Experts who viewed the video said it appeared authentic, though precisely when and where the images were recorded could not be established with certainty. Nor is it clear how many children are being trained.
Others who have tracked the recruitment of children by Syrian militant factions see the latest initiatives as intended mainly to indoctrinate young Syrians raised in a country that has a long tradition of secularist rule. The emergence of training camps for youths comes on the heels of school-outreach programs by both ISIS and Jabhat al-Nusra, which control swaths of northern and eastern Syria. Both organisations have posted videos on Twitter and YouTube showing visits to Syrian classrooms by armed militants, who hand out Islamic textbooks, as well as food and gifts.
Another self-identified ISIS video, posted in late November, shows a man in conservative Arab dress leading several dozen children in Syria's Aleppo province in denouncing a list of "infidels," including Syrian President Bashar Assad and President Barack Obama.
"Imagine we had here with us an Alawite, from al-Assad's family or religion. Would we like him?" asked the leader in Egyptian-accented Arabic.
"No," the children replied.
"What would we do with him?" the leader asks.
"Slaughter him," came the answer, in unison.
The speaker congratulates his young listeners. "Slaughter him, right. Because he is an infidel," he says.