As the "surge" begins in Afghanistan, we are told that there are early signs of success in the Nato coalition's final attempt to defeat the Taliban. But while it is true to say that in some areas -- such as the town of Marjah, in Helmand -- the Taliban appear to be giving up land without a fight, the weaknesses of the US military plan remain clear.

As the US ambassador in Kabul, Karl Eikenberry, pointed out in leaked cables to President Obama, the sanctuaries that matter most to the Taliban are not in Afghanistan at all, but just across the border in Pakistan. So long as they can hold on to these strongholds, the Taliban will bide their time and regroup once US troops begin to withdraw in 18 months' time.

The group's oft-quoted boast that "Nato has all the watches, but we have all the time" rings truer than ever.

The Taliban have learned from experience to avoid costly hand-to-hand combat, but as the assault proceeds they are likely to return and target the new Afghan security forces with roadside bombs and suicide attacks.

The surge in Afghanistan is closely modelled on that in Iraq, but is unlikely to meet with similar success. The key factor in the success of the Iraqi surge was the US recruitment of Saddam Hussein's old Sunni militias to police some of the most violent enclaves. After several years of vicious sectarian warfare, Iraq's Sunni minority had come to fear Shia militias and Iran more than the US occupation forces, and formed the "awakening councils" in response.

Yet such conditions and incentives do not exist in Afghanistan, where the Pashtuns, who dominate the Taliban, are by far the largest ethnic group and face no major sectarian or regional threat to their interests. Any attempt to "buy off" the insurgents is likely to fail, as anti-occupation sentiment shows no sign of diminishing.

At best, the surge will provide the political cover necessary for Barack Obama to withdraw with some semblance of dignity. In the meantime, the Taliban are content to sit this battle out, aware that they can strike back at a more opportune moment.

Follow the New Statesman team on Twitter.