Leading article: Nato's Afghan endgame begins with a helping hand from Russia

The Great Game reasserts itself. Dmitry Medvedev will attend Nato's summit in Lisbon next month, where the Russian President is expected to provide help for the Western military alliance's faltering mission in Afghanistan.

There is little prospect of Russia sending troops to the country, but this is, nevertheless, a remarkable turn of events. Two decades after the Soviet Union withdrew from Afghanistan, after a disastrous 10-year occupation which left 15,000 Russian troops dead, Moscow is coming back. Russian engineers are to renovate infrastructure projects, including power stations built during the Soviet occupation, and to provide helicopters for overstretched Nato forces.

Russia has a clear national security interest in stabilising Afghanistan. Moscow does not want chaos to its south when Nato forces depart. Yet the deal is also drenched in realpolitik. The quid pro quo for Russian support is understood to be that Nato will mute its support for Georgia and also rein in its ambitions for expansion into eastern Europe.

This is a bitter pill for Nato to swallow. But beggars cannot be choosers. And Nato is in an extremely weak position in Afghanistan at the moment. America is to begin withdrawing troops from next summer, despite pressure from US military commanders to keep an open-ended commitment. Our own Prime Minister, David Cameron, has stated categorically that he wants all British troops to be out by 2015. Other Nato nations long ago made it clear that they were not interested in stepping up their troop contributions. And some, such as the Netherlands, have already withdrawn their forces.

Afghanistan's neighbours are moving in, as this week's revelation of financial transfers from Iran to the Afghan President, Hamid Karzai, demonstrate. Pakistan and India are both stepping up their battle for influence in the country. And President Karzai is preparing for the departure of Nato troops by reaching out to elements within the Taliban (although not, according to reports, to the Taliban's long-standing leader, Mullah Omar).

Nato's hopes of establishing a functioning democracy with guarantees of women's rights and protection for minority groups in Afghanistan have now dissipated. The political will in the West to construct such a society (if it was ever there) has now evaporated. The best that is hoped for now is a peace deal with the Taliban and a broad-based non-intervention accord signed by the major powers in the region.

Whether Afghanistan gets this or not will largely depend on the willingness or ability of the Pakistani intelligence services to force their old Taliban clients to the negotiating table. The West's sole realistic aim is now to leave a relatively stable regime in Kabul and to maintain the ability to mount counter-terrorism operations should al-Qa'ida return to the country.

The plan does not come from out of the blue. Russia's foreign minister, Sergei Lavrov, outlined a potential deal last month, in which Russia would help to stabilise Afghanistan. And Moscow already permits the transit of certain supplies across Russian territory. An agreement is also in place allowing Nato planes to pass through Russian airspace. With Nato's land supply routes through Pakistan under increasing pressure, the logic has long been closer co-operation with Moscow.

A formal deal with Russia was always likely to be explored. For Nato, this partnership with the old enemy makes sense. But whether this latest twist in the Great Game offers a better future for the long-suffering Afghan people is, sadly, impossible at this stage to say.