The children crowd the concrete terrace halfway up the crumbling apartment block. In the corner, a 6-year-old girl with a ponytail sits hugging her legs, as she has all day, looking as if she wants to shrink and disappear into herself. She is reluctant to touch the crayons and paper that she and the other children have been given. Asked to draw what comes to mind, one boy has sketched the outline of a tank; another small boy has drawn the artillery battery outside his house. Going outside, he explains, is dangerous because of constant bombs and explosions.

The children are refugees from war-torn Syria, where fighting is in its second year, and more vicious than ever. The oldest child is 14, the youngest 3, and everyone has been uprooted from their daily lives; from school and teachers; from friends and familiar places. Some have seen relatives killed, friends blown up, or neighbors buried in rubble. But all have witnessed the horror of a country at war with itself.

Media coverage of the Syrian conflict focuses on the tangible: on the shooting and killing, on the tactics and military hardware, on the death toll and the wounded. But the harm is much greater than the estimated number of people killed—36,000 so far. The greatest casualty is the generation of Syrian children who are living with untold grief and trauma.

“I was talking with a rebel fighter the other day who told me how he and his 9-year-old son returned home after a bombing, and how they had to collect the body parts of the boy’s mother and sister into three plastic bags,” says Mohamed Khalil, a psychiatrist and director of the U.K.-based Arab Foundation for Care of Victims of War. “Skin and flesh were apparently plastered all over. The little boy said later, ‘I want to play with my mother and sister.’ He didn't fully appreciate they were dead.”

Studies in Vietnam, Palestine, and Kuwait suggest that children who witness intense violence at a young age will suffer stress disorders that can affect their neurobiology, development, and cognition, thereby scarring them permanently. Compared to children who haven’t been exposed to violent trauma, children of war experience much higher rates of depression and rage. Symptoms during the early stages include detachment and aggression as well as insomnia, bed-wetting, and nightmares. Children who suffer stress disorders also risk developing full-blown posttraumatic stress disorder (PTSD), which can give rise to suicidal thoughts and violent behavior later in life.

“We have only to look at Iraq in order to understand the potential consequences of the violence in Syria and its impact on children,” says Mike Wessells, a professor at Columbia University and author of Child Soldiers: From Violence to Protection.

Too often, he says, children who have been brutalized will reproduce the violence they experience—not because they are “bad” but because violence has saturated their environment, and become normalized. Additionally, any experiences of loss can create a desire for revenge, he warns. “The mental health and psychosocial impacts of war endure long past the time of the actual fighting.”

Khalil, for one, notes how violence is passed down among the generations. The little boy whose mother and sister were killed, he says, “has been given a 9mm handgun and goes with his father to skirmishes.”

Himself a veteran who served with Egyptian forces in the Persian Gulf War, Khalil regularly travels from London to Lebanon to work with Syrian refugees, helping out Ashraf Al Hafny, who runs a pilot program focused on children. The help is badly needed. In the northern city of Tripoli alone, where Hafny is based, there are as many as 36,000 displaced Syrian children under the age of 16, and, based on his previous work, Hafny estimates that at least one third are at risk of developing severe PTSD.

Hafny, a gentle 28-year-old from Damascus, previously worked on the other side of the equation—starting a program in 2005 to help Iraqi children who had fled with their families to Syria. Now as then, the aim is simple: to ease the children's pain and identify the most traumatized among them in a bid to prevent them from developing PTSD.

The children come from the hardest-hit areas, such as Aleppo, Idlib, Homs, and parts of Damascus, and there are few resources beyond a $60,000 grant donated by the Red Crescent of Qatar. Mostly, Hafny relies on 30-odd volunteers among the Syrian refugees in addition to a few professionals like Khalil who donate time when they can. And there are just a handful of scientific studies to guide them in their work with the children.

“There’s little out there in the region of evidence-based, peer-reviewed studies,” says Khalil. In part, it’s a result of cultural attitudes in the Middle East. “A lot of people here think that if you’re religious, you are not going to have any mental-health problems—and if you do, you’re a bad Muslim,” he says. “Syrian culture is very macho, too, and you’re not meant to admit to weakness.”

Western donors, meanwhile, prefer to work on more immediately solvable problems, such as rehabilitation of those who have been physically wounded, says Khalil. “Women and children are less visible—and so is their pain.”

In all, there are as many as 60,000 Syrian children in Lebanon, and “woefully inadequate funding” to deal with their mental-health needs, according to Annie Bodmen-Roy of Save the Children. Her organization can afford to field just one child psychologist in Lebanon. “This is scary,” she says.

Earlier this year, her colleague in Amman, Saba al-Mobaslat, sounded a similar warning of a mental-health crisis among refugee children. “We see kids running in all directions and hiding every time a plane flies over the camp,” said Mobaslat, the program director for Save the Children in Jordan. “Kids are showing symptoms of PTSD. Their drawings say a lot. It is all about dead bodies and blood. All they can talk about, draw, or describe are tanks and guns.”

Volunteers in the Kilis refugee camp on the Turkish-Syrian border have also noticed a change in the children’s behavior—there is more acting out, and most games now focus on battle and fighting, with kids running around shooting imaginary guns, or coming home with bumps and bruises after real-life scuffles. “There’s really a huge difference in the way kids play,” says Kholod al-Haj, who volunteers as a counselor for adults, and is a mother of young children herself. “It’s all about guns.”

One Kilis resident and father of five who goes by the nom de guerre Mohamed Abu Ahmed said that at this critical time when the children most need attention, their parents don’t have the time or the emotional space as they are focused on fighting and surviving. “Our whole way of thinking has been flipped,” Ahmed said. “Before, the first thing we thought about was our kids—what will their future be like, and how can we prepare for it? But now it’s the last thing we think about. We don’t have time for those things anymore.”

—With Mike Giglio in Kilis