“Neither the Government of Pakistan nor ISI (the Pakistani intelligence service) is involved in any kind of interference in Afghanistan,” he told President Karzai in Kabul. His Defence Minister’s assurance that the withdrawal did not amount to an amnesty for Osama bin Laden was not much more uplifting.

General Musharraf’s “peace deal” with Waziristan is a defeat in all but name. It follows an upsurge of popular anger in Baluchistan, which also borders Afghanistan, after Pakistani forces were accused of killing a tribal leader there last month. It leaves the Taleban and what remains of al-Qaeda’s high command free to restock their arsenals and plan future operations unmolested by a national army. And it has exasperated Mr Karzai, whose country is already threatened on several fronts by resurgent Taleban units five years after their rout at Tora Bora — and whose Nato protectors, from Britain and elsewhere, are fighting hard but not yet winning.

In Afghanistan, the approaching winter will bring a lull in fighting that Nato admits has proved far tougher than anticipated. Across the border, the Pakistani withdrawal may slow down the radicalisation of tribes-people whom the Taleban have been openly recruiting. But such optimism has seldom fostered security in the past. Waziristan’s de facto autonomy has now been formally acknowledged. General Musharraf’s own commitment to fighting extremism — and to staying in power — is not in doubt. But there are grounds to fear that some in his Government and the ISI now regard an eventual return to power by the Taleban in Afghanistan as possible, and are preparing for the transition.

This cannot be allowed to happen. It bears repeating more often than should be necessary that the case for invading Afghanistan and removing the Taleban after 9/11 was iron-clad. The moral case for maintaining the military presence necessary to rebuild the country remains as strong as ever, and the practical one for preventing the return of medievalism and state-sponsored terrorism is even stronger.

Nato’s current mission in Afghanistan was gravely mis-sold to Western voters as a low-risk project focused on civil engineering rather than enemy gun positions. It is, in fact, a major counter-insurgency effort in which defeat is not an option. It must be re-defined as such, and those leading the campaign must be given the resources they need to prevail, from helicopters to boots on the ground. The alternative is a return, five years on, to the failed, brutal, Buddhist statue-destroying state where 9/11 was conceived.