Dusk is falling over Kabul, and for Mortazar, a 17-year-old boy with an easy smile and a red waistcoat, it's time to go home. The silhouette of "TV Mountain", with its dense thicket of broadcasting towers, dominates the skyline. Every day, Mortazar stands for ten hours on one of Kabul's busiest streets, amid CD stalls and shop mannequins, hawking mobile phone top-up cards. He makes about $5 a day. "Nowadays I've almost lost interest in becoming something else," he says. "Maybe I'll be an interpreter if I can improve my English - or perhaps a footballer."
Afghanistan, seen through the eyes of its children, is a difficult mix of hope and hardship. Forty-seven per cent of Afghanistan's 33 million people are under 14. They have never known peace in their own country. Mortazar's family, tempted back to Kabul after the fall of the Taliban, is now struggling to survive in a dysfunctional city. The billions of dollars of reconstruction aid sloshing around have not touched their lives. "Because of the economic problems, I have to work," he says, "and everything is getting more expensive. Four years ago I was a refugee in Iran - at least there I could go to school."
With winter approaching, the poor are preparing for the cold. Chronic power shortages, exacerbated by a long-running drought, which has reduced the amount of power generated by hydroelectric dams, mean that families must make do with just a few hours of electricity each day. Most cannot afford generators and many will be unable to buy firewood.
"The government doesn't care for anyone," says Mortazar. "It's just stealing money and doing everything for itself. When the foreigners are watching, they behave. But as soon as backs are turned they just take whatever it is - blankets, food, whatever - and sell it. I've seen it happen. My sister has, too. A charity came to her school and started giving out stationery: when the foreigners left, the rest just went missing."
Saleem, a slight, ten-year-old boy with kohl smudges beneath his eyes, is more sanguine. "Whatever you say about it," he says, referring to the government, "it's better than the Taliban." His cousin Fareed doesn't comment. He is absorbed in trying to mend a battered bicycle wheel.
Fareed's bicycle repair shop is located on a dusty slip road not far from Kabul airport. Chickens scratch for food in the rubbish strewn all around, and the neighbourhood of mud and brick houses that stretches out behind is one of Kabul's poorest. "I'm open early morning until late at night," he announces proudly, glancing up at a sky pierced by a single, bright star. With calloused hands, an oily salwar kameez and serious eyes, Fareed looks older than his 15 years. He did not grow up; he was just forced by circumstance to become an adult. He doesn't go to school and his business brings in, on average, a dollar a day. "Things are not great right now," he concedes, struggling with an inflated inner tube. "But they'll soon be looking up." "The next few years are going to be good," Saleem agrees with enthusiasm, though he is unable to say why they will be good.
All the signs are that they won't be good. The insurgents, with safe havens in Pakistan's tribal areas, are well-resourced and growing stronger. Robbers and kidnappers operate with impunity and Afghans travelling by road are sometimes stopped by militants and searched for any evid ence of involvement with foreign companies or NGOs: the wrong business card in your wallet or number in your mobile phone can get you killed.
President Hamid Karzai, up for re-election in 2009, is widely perceived as indecisive and his government as corrupt. Politicians have built mansions in wealthy Kabul neighbourhoods such as Sher Pur, and Karzai's own brother, Ahmed Wali, has been accused of involvement in opium trafficking, which he denies. Last month's cabinet reshuffle came too late to inspire much confidence and relations with the British have been poisoned by a series of incidents, notably Karzai's refusal in January to accept Lord Paddy Ashdown's appointment as UN envoy in Afghanistan. The police, riddled with corruption, are in desperate need of reform, and the Afghan army, though improving, is still under-strength and unreliable.
Civilian casualties have eroded public support for Nato troops and it remains to be seen if, under Barack Obama, the troop surge will make things better or worse. Leaks and contradictory statements from the Afghan government and its western allies reveal uncertainty and division. Tentative negotiations in Saudi Arabia have shown that the militants are in no mood for deal-making - this winter, there may be no respite before the inevitable spring offensive.
Along way from the bustle, dust and razor wire of Kabul, villagers in Keshem, a district in the north-eastern province of Badakhshan, are gathering the harvest. Donkeys smothered beneath thick loads of fresh hay are driven along narrow roads hemmed in by high mud walls and clear, fast-flowing irrigation channels. The fertile Keshem valley, once famous for its poppies, is at peace.
At Jari Shah Baba girls' school, the tranquil sound of children learning Dari - a variant of the Persian language spoken in northern and western Afghanistan - by rote drifts in through the open windows of one of the classrooms. Out of a class of 15 girls aged 13, all in neat white headscarves, just one has a mother who went to school. But there is change, largely because of economic reasons. The girls here say that their fathers now support them going to school and, when asked what they would like to be when they finish studying, most shout out "doctor", "teacher" or "engineer". Educated girls make more money.
Two new school buildings are under construction with money raised by Afghan Connection, a British charity that, working closely with the Swedish Committee for Afghanistan, has so far financed the building of 30 schools for more than 30,000 children. Jari Shah Baba is one of many good news stories that can be found in Afghanistan.
Children hurry along corridors and play in the grounds outside. The air of eager optimism, in and out of the classroom, is unmistakable. "We want to work to improve Afghanistan so that it can be like other countries," is the line often repeated, but always with conviction.
The students say they are not worried about security and seem unwilling to think about it. "I used to watch the news," says one of the girls. "But it's always bombing and killing. We're bored with the fighting - we don't want to hear about it any more. I prefer to watch Indian soap operas."
Still, even in Badakhshan, the indicators of war are all around. Empty shell casings do for school bells, old Soviet tanks lie sunk in the grass, and red and green flags flutter by the roadside (marking landmines and martyrs' graves). Many Afghan officials predict that it is only a matter of time until the insurgency spreads this far north. But for now, thoughts are on future dreams.
"I want to go to university and study medicine," says 19-year-old Zulfiya. "But it's difficult." Zulfiya is fortunate to have her father's support. Of the 1,150 students at Jari Shah Baba, approximately 400 are married and many of these are already looking after their first child. Burkhas, belonging to the older girls, hang inside classrooms ready for the journey home. Expressive faces vanish suddenly behind blue nylon. For those able to compete for a place at one of Afghanistan's few state-run universities, competition is stiff. Last year, 35,000 students took the entrance exam; there was space for 10,000.
Kourban, a student from Sang Boran boys' school in nearby Baghlan province, is not worried about passing the exam - he has always been top of his class - he is worried about paying for his studies. "I'll face a lot of financial problems," he says. "I know people who dropped out after one or two years at university because they couldn't afford it."
Neither of his parents went to school and just one of his three older brothers can read and write. The family makes its living farming and there isn't enough left over to support a son studying in the city. Now aged 20, Kourban has had to spend time catching up on school years missed during the fighting.
Through Afghan Connection, his school is "twinned" to Eton College: the students exchange gifts and letters in order to attain a mutual understanding. Kourban's demeanour is usually one of calm determination but, when confronted by photographs of Eton's grand architecture and oddly attired students, he is momentarily bemused. "Can I have a scholarship?" he asks, eventually.
Like many Afghans, Kourban believes that Afghan istan would collapse in all-out war if the foreign troops were to leave. His attitude is pragmatic: "We don't have a military force capable of controlling the country," he says. "So for now, it's better for the foreigners to stay."
Others are not so sure: "If the foreigners went away, I think the problems would go with them," says Abdu Rahmin, a 14-year-old boy from Khost, a troubled province in the east that borders North Waziristan, one of Pakistan's most militant-run tribal agencies. "A roadside bomb exploded when foreign troops were driving past my school. My friend was injured in the blast; now I'm always scared something will happen."
His story, and lasting anxiety, is not unique. “My sister-in-law was killed in a bomb blast,” says Nabila, a 13-year-old girl, also from Khost. “When I go to school, I am afraid there will be a bomb on the way; when I get there I start worrying about my father – especially when he goes to the city because there are lots of security problems there.”
Afghanistan's children have learnt the vocabulary of war. When talking about violence, they quickly reduce their experiences to specifics. Terms like "security", "suicide attack" and "roadside bomb" are deftly employed by children younger than Nabila and Abdu Rahmin. These are the words used to describe their world.
"The Afghan government cannot make 30 per cent security for the people," says Abdu Rahmin, angrily. "That is the big failure and disappointment. The Taliban were bad: they didn't like music or fashionable clothes, but the one important point is that when they were in charge, we were safe."
Nabila is not interested in taking sides. Her father is old and she has no brothers to help support the family. She is worried about money, and about losing her parents and maybe being blown up. But, when asked how she compares life under the Taliban with life now, she answers without hesitation: "In the Taliban time, there was security; in this time, no." She is equally matter of fact when asked about the foreign soldiers: "I don't know about them any more. Since they came to Afghanistan, there has been more killing."
Across the border in Pakistan, a tilted half-moon hangs in the black sky above Aza Khel Afghan refugee camp in Nowshera, a district of the North-West Frontier Province, and the call to prayer rings out over the vast community of flat-roofed mud houses. People here are deeply distrustful of western involvement in Afghanistan. Militants hide among the houses.
"They say there is a problem in Afghanistan and that they are there to fix it," says Hairullah, a confident 16-year-old boy whose family originally came from Nangrahar, a province in eastern Afghanistan. "Then they say there is another problem, so they need to stay. It's obvious the soldiers are just there to cover Afghanistan and make it part of the United States."
His brothers nod in agreement. Hairullah is one of more than three million Afghan refugees living in Pakistan. He has visited Afghanistan just once, four years ago. The camp is located next to a river on the other side of the railway tracks that run along the main road. Floods regularly damage the houses and conditions are basic, but at least there is mains electricity most of the time. Many of the 9,000 families living in Aza Khel have been here as long as 30 years. Despite this, the atmosphere is one of uncertainty and impermanence.
For Hairullah, there is no question of staying. "As soon as I am a doctor," he says, "I am going back to Afghanistan to help my people. I want to make my country strong."
"I'm going, too!" interrupts his brother, Zaidullah, a small, outspoken 11-year-old. He is dressed in a turquoise salwar kameez.
"I don't like being away from my homeland. When I am taller, I am going back to help my country."
Sam Alexandroni was awarded a 2008 Winston Churchill Travelling Fellowship. For more information on the Winston Churchill Memorial Trust visit http://wcmt.org.uk 
For more information on Afghan Connection visit http://afghanconnection.org