Five years ago the former King of Afghanistan, Mohammad Zahir Shah, addressed 500 delegates at a Loya Jirga in a vast tent in Kabul. Their purpose was to plot their country’s course from warzone to democratic state. For most Afghans the occasion was as auspicious as the liberation of Kabul two years earlier. “We are doves, waiting for peace, tired of fighting,” the former King said, and he seemed to speak for everyone.

Thanks to the Taleban, the fighting has continued. That it has not overrun the country is a tribute largely to the British and North American forces leading Nato’s International Security Assistance Force. At mounting cost in blood and treasure, including, now, 100 British lives, they have held the Taleban at bay and enabled reconstruction to begin. They have done so despite the constant replenishment of Taleban forces from Pakistan’s tribal areas, and the internal tensions of a 37-nation force, some of whose pilots are not allowed to fly at night.

Britain’s forces in Helmand deserve nothing but our admiration, thanks and praise. The same cannot be said of the civilian governance bequeathed by that historic Loya Jirga. Five years on Kabul’s writ scarcely extends beyond the city limits. Warlords retain control of most northern provinces. The Taleban have quietly reimposed Sharia in Kandahar. What civil service existed in 2001 has defected en masse to serve the tangle of aid agencies that constitutes Kabul’s main industry. In rural Afghanistan, opium rules. Corruption, everywhere, is rampant.

Against this background President Karzai will this week seek £25 billion in aid in addition to £12.7 billion already pledged and £7.6 billion spent. Mr Karzai is not to be envied. Afghanistan has never known effective central government. Nor is he to be faulted for his optimism: if virtually unlimited foreign aid were a proven strategy for building stability from the wreckage of a failed state, he should ask for it. But it is not.

Mr Karzai and the international community can boast of significant progress is certain areas, including road-building and healthcare. But there is evidence that a new flood of aid at this stage would delay the creation of the civil society that Afghanistan needs most.

There are two broad reasons for this. The first is the disruption caused whenever ill-co-ordinated armies of NGOs descend on countries that are unprepared for them – by siphoning talent away from ministries, duplicating each other’s work, wasting their own money and fuelling aid-dependency and corruption. Hence a former finance minister’s complaint of having to field 16 competing plans to reform the Afghan Justice Ministry. Hence, too, the “salami slicing” of construction funds so that one plan to rebuild a village yielded only a few months’ firewood.

The second reason donors should listen sceptically to Mr Karzai is Mr Karzai himself. He has been fêted for preserving the basic machinery of democracy against daunting odds. But by resisting the appointment of an experienced co-ordina-tor of foreign aid and military efforts he has sharply limited the world’s ability to help him. And by turning a blind eye to corruption, including, apparently, in his inner circle, he has failed to turn his own patronage into real power.

As 9/11 showed, the world cannot afford a failed state in Afghanistan. That is why Nato is deployed there. It is why 100 British men have made a noble sacrifice and why a war-weary and weak scuttle from Helmand is not an option. However gloomy the lessons of history and however long it takes, Britain must stay the course. But the military mission will be forlorn without political progress. It is up to Mr Karzai and his Government to show that they are worthy of the cost in blood being borne by their allies.