CHARRED BODIES littered the building, the victims of a suicide bomber who had penetrated security at one of the most heavily-guarded sites in Kabul.

A Taliban spokesman gloatingly confirmed that the attack was aimed at the ministry's western advisers, part of a strategy of terror against the capital of Afghanistan's foreign aid community that saw British worker Gayle Williams shot dead two weeks ago.

It was a stark reminder of the violent campaign waged by the Taliban in Afghanistan - and of the scale of the task facing the American general ordered to claw back victory from the jaws of what is starting to look like defeat.

Gen David Petraeus, the "warrior-scholar'' credited with working a miracle in Iraq, is taking command of the war that America forgot.

On Friday, he started as the head of US Central Command with orders to send more troops to Afghanistan, devise new tactics, and work out a strategy that, after years of muddle, bloodshed and drift under Nato's confused command, will take the battle to the Taliban and win the war.

His old enemy appears to be planning its own surge.

US intelligence believes that Arab jihadists have been arriving in the Pakistan borderlands as Iraq cools and Afghanistan hots up. American commanders have barely bothered to disguise their growing frustration with their European and Nato allies whose war has been uncoordinated and inadequately resourced. Major military forces from Germany and France have avoided sending their troops to Taliban-dominated areas, while Holland and Canada, whose soldiers have seen ferocious fighting, will soon restrict their troops to training Afghans.

It is clear from their actions that many of America's allies increasingly believe that the war is unwinnable and not a place to put any more troops in harm's way.

American commanders have looked at all the options in a thorough review and come to a different conclusion - they have decided that now is the time to fight.

"What will eventually win this war is American military power,'' said a senior Nato source in Kabul. "There is no question of America withdrawing from Afghanistan. They are not prepared to let the people responsible for September 11 move back in.

"If the Europeans decided to go they wouldn't be missed that much, frankly. Some of them are in the way.''

The plan for Afghanistan will almost certainly be very different from the successful strategy in Iraq, where a short-term but massive surge of troops proved instrumental in achieving a degree of peace. Gen Petraeus has repeatedly stressed that the Afghan challenge is different. Indeed, some of his army rivals consider him more lucky than brilliant - he took command just as the Sunnis had become sickened by the bloody excesses of al-Qaeda in Iraq, and they were in a mood to strike deals with Americans.

In Afghanistan, although the Taliban is not popular, its support is growing. And Gen Petraeus will not have enough manpower to flood the villages and mountains along the Pakistan border.

Instead, American commanders are understood to be preparing to present the new president in Washington, whoever he is, with plans to fight an intense five-year war against the guerrillas, a war that commanders think looks winnable, unlike the morass the troops are in now.

Britain will remain a key partner but battles in Helmand will increasingly be fought by American combat troops and American commanders will call the shots. A serious effort will also be made, at last, to get a grip on the crippling problems of Kabul's corrupt government.

"President Karzai will be told bluntly that it is time for the Kabul government to change its ways,'' the Nato source said. "They will have to look like a government worth fighting for.''

President Karzai, who rarely leaves the gloomy confines of Kabul's Arg Palace, is said, even by his own supporters, to be exhausted. He still plans to stand in next year's presidential elections, much to the dismay of most Westerners and plenty of Afghans, too.

The US is so fed up with corrupt and inefficient Afghan police and security forces that it is already considering arming village militias - a plan that sounds very similar to the Sunni Awakening programme that successfully energised Iraqis against al-Qaeda.

Afghans fear that it could instead make petty warlords more powerful, and point to the fact that historically, every western dalliance with warlords in Afghanistan has been a disaster: the Taliban itself was an indirect by-product of US funding of the mujahideen movements against the occupying Soviets in the Eighties.

The other radical new element of America's strategy will be talking to the Taliban. But this will be less an attempt to come up with a grand deal, and more an effort to split and demoralise the enemy.

It risks backfiring if anti-Taliban Afghans think a deal will be a fig leaf for Britain and America to pull out and leave them to their fate. The US military will have to prove itself to be an instrument of persuasion for America's Afghan supporters who are waiting to see if it really means to win.

Nick Day, the CEO of Diligence Global Business Intelligence and a former Special Boat Service officer and British Intelligence agent who now monitors Islamist groups, said increased US military power could win the war.

He said: "All the drone aircraft and helicopters they can bring in will make a huge difference, and the Americans have learned a lot about counter-insurgency in Iraq. Their soldiers are professional and committed. Once the violence level has been dampened down, then it will be time to look for an exit.''

What is not clear, however, is how many more troops Gen Petraeus will have.

The US military is exhausted after years in Iraq, from where the general plans gradually to withdraw his men.

US commanders have asked for 20,000 more soldiers to reinforce the 64,000 Western troops in Afghanistan, but so far the Pentagon has approved one brigade - about 4,000.

More will arrive next summer, but they will certainly be less than the 30,000 extra troops sent to Iraq for last year's troop surge.

If they prove to be not enough, and if the jihadists continue to flock in, American troops could find themselves struggling in a bloody quagmire instead of getting to grips with the Taliban.

The Soviets, after all, sent 140,000 men to fight Afghan guerrillas at the height of their war and still lost.

As fresh American troops drive between their bases next year, past ambush points and along roads where the ground can erupt at any moment in a minestrike, they will often see the carcases of Soviet tanks.

They may reflect that every other army that has tried to win Afghanistan by sending in more troops has left the same way; in humiliation and defeat.