There is a constant threat from sophisticated IEDs on Afghan roads Photo: AP

Commander Yusef hunched his shoulders against the wind tearing down Highway One and warily scanned the snowy hills. Of course security had improved on the road he said, unconvincingly, as his men checked their weapons.

But he advised against joining the minibuses and overladen, hand-painted trucks which were driving farther south along Afghanistan’s main highway.

Three times Taliban fighters from the hills had rained rockets and machine gun fire onto the mud-walled house and shipping container which formed his Spartan checkpoint since he took over.

“The last time they attacked with 30 men and we fought from evening until dawn,” said the 35-year-old policeman, a former mujahideen fighter.

Thirty miles further south the roadsides were littered with the burnt carcasses of Nato supply lorries left to rust in the rain, the aftermath of almost daily attacks.

Western soldiers must push their supply convoys down this road to the battlefields of Kandahar and Helmand Provinces at the far end – and the Taliban attack them as often as they can, killing their Afghan drivers and destroying the lorries.

As the coalition campaign enters its ninth year, the main road linking the capital Kabul to Kandahar is an illustration of the colossal challenge now facing President Barack Obama and his allies.

Gen Stanley McChrystal, the senior Nato commander, has nearly 110,000 international troops to fight his war. But they have failed to protect the cities and surrounding farmlands where most Afghans live, and the communication links which hold them together – and on which the shaky control of the government in Kabul relies. The roads themselves were safer for travellers when the Taliban were in control, Maj Gen Nick Carter, Britain’s most senior commander in Helmand admitted last week.

The new surge strategy announced by Mr Obama has a goal of winning the support of the Afghan people by protecting them from Taliban fighters in the settlements where they live and on the roads they must travel.

But at commander Yusef’s checkpoint, only 15 miles from the Kabul city boundary, the scale of the challenge the US soldiers have set themselves was apparent.

Afghans wanting to travel between the capital and the second city must run a gauntlet of robbers, Taliban ambushes and jumpy American convoys, which are heavily armed and ready to open fire.

Lorry drivers paid danger money to take military supplies along the road complain that their convoys are attacked during every journey they make, despite hundreds of US troops trying to secure the route.

Mr Obama has now given just 30,000 more troops to break the back of the insurgency and in 18 months those troops will begin to go home.

Gen McChrystal may be confident it can be done; but the passengers and drivers who take their lives into their own hands each time they travel the roads are not. And after eight years of unfulfilled promises and growing death tolls, they are not sure that more American troops are the answer.

Karim, a lanky Pashtun from Ghazni – with only one name, like many Afghans – would rather not risk his life driving the highway for £75 a month, but he has little choice if he wants to feed his eight children.

“The situation gets worse day by day,” he said, raising his eyes to heaven as he again prepared to climb into his coach and drive down the road. “My family don’t like it, but what can I do? It’s better than staying at home with no food.”

The 42-year-old’s coach had been held up by robbers who went through his passengers’ pockets at gunpoint, and searched by Taliban patrols looking for government workers.

But he reserved his greatest anger for the American convoys that were supposed to be securing the road. The six-hour drive to Kandahar often took four times as long because his bus became stuck behind lumbering mine-proof lorries and was frequently pulled to the side of the road for searches.

Any attempt to overtake US troops or get too close was answered by a rock flung by a turret gunner at his windscreen, or by a shot ricocheting off the road.

“The main trouble is with the Americans,” he said. “If they have come to help us they are most welcome, but if they are just here to hold us up and cause trouble, we are not happy.”

He was enthusiastically supported by Ismatullah, another driver who pointed out a bullet hole in his windscreen covered by a sticker. “Unfortunately there is fighting between the Americans and the Taliban along the road,” he said.

“The Americans don’t care if you are a civilian or a driver, they just shoot. If an American gets hurt then they shoot everyone.”

Gen McChrystal knows how damaging these accusations are and has said he knows that the battle for Afghanistan is a battle of perceptions.

“At the end of the day it’s not the number of people we kill, it’s the number of people we convince,” he told his troops as he briefed them on the surge last week. “It’s the number of people that don’t get killed.”

His battle to win over an increasingly distant Afghan population is not the only hurdle he faces. United States officials admit his plan to train the Afghan army and police while repelling the insurgency and making space and time to strengthen the government will be “hard”.

“Success is not guaranteed,” said one senior diplomat.

Behind the public optimism, officials worry about how difficult it will be to transform a rag-tag collection of illiterate Afghan police, under the influence of drugs much of the time, into an effective force.

They also worry about whether they can close the gulf of alienation and distrust between Hamid Karzai’s weak and corrupt regime and those living in the southern provinces, the main battlefield in the war against the Taliban.

General Hilaluddin Hilal, a deputy interior minister in the early years of the Karzai government, said that without more help from Pakistan American hopes were doomed. “The new strategy from Obama doesn’t consider our neighbours enough,” he said.

“Pakistan is still not doing anything to destroy the Taliban or insurgents like Gulbuddin Hekmatyar or Jalaluddin Haqqani. The Taliban still have safe havens in Pakistan. This is a big problem for the strategy.

“People are very worried that if Obama says they will leave in two years, the Taliban will get ready. They think that in two years the Taliban will attack everything.”

Most of the new US troops will be sent to Helmand, where beleaguered British forces have been locked in fighting for nearly four years, and to Afghanistan’s second city of Kandahar.

Gen McChrystal has said he will do whatever is necessary to secure the southern city – a key target for the Taliban – and reverse its quickening slide into anarchy.

Four years after the Taliban resurgence began in earnest, the city is under virtual siege with Taliban controlling large areas beyond the city boundaries – and even large areas within it. Anti-Taliban mullahs and leaders are assassinated, crime is rampant, and kidnapping is a booming business.

“If you have any money they will kidnap you and if you work with the government they will kill you,” said Rahim Khan, a 50-year-old businessman who had arrived in Kabul on a bus from Kandahar.

“Life is getting very bad there,” he shrugged.

And yet, despite all this, he said he had no faith in Gen McChrystal’s promise to protect the Afghan people from the Taliban.

“Kandaharis hate the foreigners now,” he said. “If they send more troops it will only make the situation worse. Afghans will join together and turn on the foreigners.

“So many people are going to join the Taliban. The fighting is at the gates of the city and all through the countryside.”

Kandahar holds enormous symbolic value to the insurgents as the city where the Taliban first rose to prominence and where their one-eyed leader Mullah Omar was acclaimed Commander of the Faithful. For several years the city and its districts have been garrisoned by a couple of thousand Canadian troops who have suffered high casualties.

International officials admit the government only holds sway in the city during office hours and at night officials and police lock themselves in and pray that they will survive the night. With reinforcements, US commanders hope they can finally secure the city of between 800,000 to 1.3 million people by first throwing a ring of troops around it.

Under Gen McChrystal’s plan Canadian troops and new American arrivals would keep the Taliban at bay, while diplomats and aid workers would try to strengthen the woeful government.

Azizullah, another businessman from the city, said his younger cousin had been forced to send his family to Herat for protection when the Taliban found he was working at Kandahar’s military airport.

But the 23-year-old still thought more American troops would only provoke violence. “The people will not be happy if they send more Americans,” he said.

At the other end of the highway at the checkpoint near Kabul, Commander Yusef tutted as he showed how badly made the new US-made weapons were that he had been given, in comparison to his old trusty AK-47.

But he is clear where the responsibility for any eventual success must lie.

“It’s our country and we have to build it because for 30 years we have seen nothing but fighting. We have to build our home because no one else can do it for us.”