Afghan warlord Mohamed Humayun controls an army of 300 battle-hardened soldiers, six tanks and a BM-21 multiple-barrelled rocket launcher. Not bad for a 15-year-old. While most teenagers dream of motorbikes and staying up late, Humayun is busy fighting his own private war on the side of his country's Northern Alliance.

He gained control of this little empire three months ago when his father, Aghagan (40) was killed in a Taliban rocket attack. Since then the valley and all the people in it have passed to his son.

Standing on the roof of his sprawling mud-brick compound in the village of Bolak Kushlaq, Humayun is quite literally king of all he surveys.

Stretching out in every direction are the brown parched fields and scattered settlements of the 26 hamlets and villages under his control.

Rising sharply to the north and west are the jagged peaks of the outstretched fingers of the great Hindu Kush, their brown sides flecked at the top with the first snows of winter. And behind the peaks are the Taliban.

His father's death has also put Humayun in charge of his mother, his father's two other wives and a total of seven brothers and three sisters, all younger than he.

"It is a big responsibility but I am used to it," he says. "I was my father's deputy. When he died, I was very sad. Very sad. But then I understood I am a man."

When he assumed command, his first decision was to recruit 70 former pupils from his old school to fight in his army. And he made his cousin, Juma Khan (16) his personal bodyguard.

"Children make great soldiers," says Humayun. "In the West you have the wrong idea about this. Children are strong and fast, and they are very brave."

His self-confidence is bewildering. He strides among his giant soldiers like a little Napoleon. He is already married, to Jamila, a girl of the same age he met at school. She lives with his mother in the nearby town of Kalafgan, far away from the fighting.

Aid officials say child soldiering is a product of a society which puts clan loyalties ahead of anything else. "This case reflects the reality of Afghanistan's problems - you have the leading family where a man died only to be replaced by his oldest son," said Red Cross official Eloi Fillion. "It's like succession for a king."

To be Humayun's guest is to experience the court of the Sun King. Munching on a banquet of meat and potatoes, bread and apples, nuts and raisins and endless cups of sweet green tea, watched by his adoring soldiers, Humayun explains his responsibilities.

"My system is simple," he says. "All the time I split my men - 150 to the front line and 150 here.

"The war takes up all my time. There is no time for computer games." The star piece of kit is the truck-mounted BM-21 Russian made rocket launcher, a fearsome weapon which can fire 40 three-metre rockets.

This is not only a devastating weapon, but the Afghan equivalent of owning a Lear jet.

With a rare touch of modesty, he adds: "You know, the tanks and rocket launcher are not really mine. They belong to the government. The government has made them mine to use."

Humayun's soldiers are a rock in the Alliance front line - one reason why, when they transferred their loyalty to a 15-year-old, even the president does not interfere.

In fact the Northern Alliance president, Burhanuddin Rabbani, is a fan, securing Humayun's loyalty by offering to pull strings to get him a university education in London when the war is over. "Do you think Juma Khan will have a problem taking his gun over there?" he asks, pointing to the boy's Kalashnikov machine-gun. I tell him yes. "How about a pistol?" he asks hopefully.

Evening draws in, with the orange setting sun momentarily lighting up the far hills. Darkness falls fast here. A petrol lamp is produced. Humayun's face, already young, now looks positively cherubic.

For all his youth, he shows more knowledge of the outside world than most other warlords."The problem for Afghanistan has always been the foreigners. It is their meddling that creates these wars," he says. "If all the forces leave there will be peace here."

Then, with politics out of the way, he turns to other matters. He pats the cushion next to him and nods at my Norwegian colleague, reporter Osne Seierstad - whose name, it is pointed out, means beauty in Dari. She obeys the summons and sits next to him as all the other soldiers stare. We have moved from Sun King to the King and I.

"You are very beautiful," he says. "Could you tell me, in the West do ugly women find husbands?" She says yes."That is good," he says sagely. "In Afghanistan, a woman who is ugly will not get a husband. But still it can be all right for her, as long as she learns a skill. Like making carpets."

As the evening draws on, he relaxes, and is not afraid to pick his nose in public. There is an awkward pause when the picking triggers a nose bleed - and a dozen flunkies rush to offer their neckscarves to mop up the blood.

"Sometimes people do think I am just a child," he confides. "I went visiting the foreign ministry in Hoja Bowdin. At the gate the guard would not let me in. He told me I was a child." He pauses, staring at my colleague, letting the words sink in.

"I was angry. Later of course the man realised his mistake. He brought me tea. But," he adds ominously, "I did not drink it." And, you suspect, that is one man who will not be journeying into the Bolak Koshaq valley.

Next morning he takes us to his rocket launcher. As Humayun arranges his men for a photograph, an elderly man, Yakop, steps forward, walking with the aid of a long brown leather-bound cane. Yakop explains that he is one of three uncles who "advise" their chief on military matters.

But what if he ignores their advice? This causes a moment of embarrassment on the face of the uncle, surrounded as he is by Humayun's foot soldiers.

"Look, it is like this. Humayun is the leader. It is only advice. But he always accepts it."

And then it is time to go: Humayun bids us a happy farewell, and then the royal jeep is prepared. He says he must go.

To the front line? "No," he says, suddenly bashful. "I must have my hair cut."