The image burns itself into your brain: little Omran from the Syrian city of Aleppo sitting in an ambulance, staring into space, covered in blood, clothes torn, his hair full of dust. The photograph, taken by an activist a few weeks ago, provoked horror around the world. We can only surmise from this little child's stunned expression what the war in his homeland has done to him, and to many other children and youngsters like him.

Aleppo has again been forced to endure weeks of bombing by the Syrian and Russian regimes. A ceasefire was in place over the weekend. Of all the cities caught up in the Syrian civil war, Aleppo is the most fiercely contested. According to the UN, more than 250,000 people are trapped under siege in the eastern part of town. The recent bombardments were the heaviest since the start of the war in 2011. In the last offensive alone, which began on September 22, more than 500 people were killed and 2,000 wounded. Around a quarter of the victims were children - and that number could rise dramatically, as the United Nations International Children's Emergency Fund (UNICEF) estimates that there are around 100,000 children and young people in eastern Aleppo.

'Medieval conditions'

In an October 21 speech via video link to the UN Human Rights Council in Geneva, the UN High Commissioner for Human Rights, Zeid Raad al Hussein, said the siege and bombardment of Aleppo "constitute crimes of historic proportions." This ancient Syrian city, "a place of millennial civility and beauty," was today, he said, "a slaughterhouse."

Although Russia agreed to the ceasefire, the sick and injured could not be brought out of the city. The United Nations said it was unsafe to transport them, and secretary-general Ban Ki Moon pointed out that: "Under these medieval conditions, the vulnerable are suffering the most."

Suicidal thoughts among children

Katharina Ebel, the project advisor of SOS Children's Villages in Syria, confirmed that this is indeed the case. The children are under tremendous psychological strain, she said, warning of severe depression that could even lead to children having suicidal thoughts. "One boy who wanted to take his own life was only 12 years old," she told the "Passauer Neue Presse" newspaper.

"So far we've always been able to prevent children from killing themselves," Ebel went on. But she reported that every day there are children who say, "I'd rather die than go on like this." Deep depression drives them to commit acts of aggression, against both themselves and others. "Many of them can't sleep any more, or have nightmares, and then they're completely exhausted during the day," she said.

Children describe the rigors of their everyday lives on the website of UNICEF's #ChildrenofSyria campaign. Not only do they risk being killed on the way to school, the schools themselves are also often attacked - around 4,000 times since the war began. And even those who try to take shelter may be killed: The organization Save the Children has reported that so-called "bunker buster" bombs are being used.

Some experiences are too extreme

SOS Children's Villages have psychologists and social workers in every facility, "who talk to the children individually, try to alleviate their trauma, restore the children's sense of trust," Ebel said. "Sometimes it's just not possible, because what they've experienced is too extreme. Often, when a child has seen their parents die, seen them buried under rubble, seen their home destroyed, their sense of security is lost for a very long time."

The Syrian winter will start to set in in just a few weeks' time. UNICEF warns that many children and their families have reached the end of their strength. Children are especially at risk from the freezing temperatures and snowstorms that have often occurred in recent years. The aid organization is also very worried about the children in the Iraqi city of Mosul, 600 kilometers (370 miles) further east. It warns that the current offensive to recapture the city means the more than 500,000 children and their families there are now in extreme danger.