Bored at home and eager to join their older brothers and fathers on the frontline against President Bashar al-Assad's army, Syrian teenagers are joining the rebel cause, oblivious to international laws prohibiting child combattants.
"When they arrive here, they are children. By the time they leave, they are killing machines," said Abdel Razzaq, a 38-year-old former army sergeant who trains the boys.
"I train them not to be scared of war and not to hesitate when the time comes to kill," he said, speaking of his latest group of 20 volunteers, aged 14 to 18.
"There are no more adult men in the villages. Now it's the children who come for military training," said Abdel Razzaq.
He teaches his students how to handle a Kalashnikov, or AK-47 assault rifle, the weapon most commonly used by the rebels.
He teaches them how to disarm an enemy and kill him with a knife or even their bare hands.
"Children are the best soldiers I know. They obey every command. An adult asks questions and answers back. But the children, they question nothing," said Abdel Razzaq.
"Musab, you're supposed to kill your opponent, not caress him!" he shouted out as he watched a 14-year-old boy try to disarm an opponent with a punch rather than by stabbing him.
Musab's father said he takes pride in his son, who he's sure will make "a very good soldier".
Sobhi, aged 15, said he begged his father to allow him to start training.
"I was tired of staying home, waiting for my father and brothers to return from the front to tell me about the war. I want to go to the front and see it with my own eyes," he told AFP.
Abdel Razzaq's "military academy" is a former school, located in northern Syria's Aleppo province. Before being sent off to the front, the boys receive two hours of training a day for three months.
The boys' families are eager that they are trained well before they are sent off to fight the army.
"Without proper training, they would die quickly," said Abdel Razzaq.
Fifteen-year-old Mohammed seems to have quickly learned how to assemble and dismantle his Kalashnikov.
"Ready!" he said proudly, showing off to the instructor, a figure of both respect and fear for the boys.
Bashar, aged 16, was signed up for training by his brothers. "I want to avenge the death of my father," a rebel Free Syrian Army fighter, he said.
With families willing to bring their boys forward for training, Abdel Razzaq's academy does not need to go into forced recruitment.
UNICEF child protection coordinator Jean-Nicolas Beuze told AFP that, "unlike other conflicts, there is no active recruitment of children. The youth come spontaneously, encouraged by their families."
But Beuze said "commanders have the obligation to turn them away."
International law prohibits the use of anyone under the age of 18 in combat and in military support operations, such as espionage, transporting weapons or providing supplies to fighters.
The use of children "as combattants or as a support to combattants constitutes a grave violation of children's rights," said Beuze.
Rights groups have frequently accused both the regime and the rebels of rights abuses in a war that has left more than 3,500 children dead, according to monitors.
Several amateur videos have shown child soldiers in flashpoints across the country.
Distributed by the media or even by rebel groups turning child soldiers into trophies, several videos have shown young boys brandishing Kalashnikovs and other weapons.
One video shot in the eastern province of Deir Ezzor showed a young boy holding an automatic rifle, as rebels fired their weapons nearby.
"This is the youngest fighter in Syria," said the unidentified cameraman shooting the video. The boy introduces himself as "Danny Walid, aged 14."
Another video widely circulated by regime supporters showed shocking images of a young boy surrounded by men identified as rebels.
The axe-wielding boy beheads a man stretched out on the ground. The men congratulate him, and then kick the severed head at the boy's feet.
Syria's conflict broke out in mid-March 2011 as a peaceful uprising but morphed into a bloody insurgency when Assad's regime unleashed a brutal crackdown on dissent.