It may seem a phoney war, but that cannot last

American warplanes pounded Kabul, the Afghan capita, and a military base in the eastern city of Jalalabad yesterday as the air war against the Taliban and Osama bin Laden entered its second week.

But the soldiers who mill about in the villages behind the opposition front line north of Kabul have the air of men who are expecting great events and are a little bemused by the fact that so little is happening in their sector.

The sense that it is a phoney war is almost palpable. The first aid stations, hastily cleared of non-urgent cases two weeks ago to make way for the casualties of war, are empty aside from a few farmers who were injured by mines while they worked in their fields.

It cannot last. The Northern Alliance promised it would launch a military offensive against the Taliban a few days after the American bombing started. Its commanders say they are waiting for the United States to hit frontline Taliban positions.

This is easier said than done. The Shomali plain, which has been divided between the Northern Alliance and the Taliban for five years, is heavily populated. American bombing would kill many of the civilians who are still living in their half-ruined villages.

But the nature of the front in northern Afghan militates against the effective use of air power. The very words "front line" evoke images of the Western Front in the First World War, with opposing armies crouched in well-defended trenches protected by machine- guns and barbed wire.

Afghanistan is not like that. Armies are small. The Taliban has 60,000 men and the Northern Alliance has 15,000, though both can increase their numbers using local militias. Front lines are usually a tripwire, held by few men, with forces for counter-attacks held further to the rear. "Fighting here is partly like regular warfare using fixed positions and partly like guerrilla war," said General Babajan, who commands the Northern Alliance's forces at Bagram airport.

War in northern Afghanistan has other peculiarities. There are few roads and where they do exist they are atrocious. Most of the big bridges were blown up in the past 10 years. Both sides have tanks, but, as the countless wrecks beside the roads testify, these are easy to ambush and destroy.

The Northern Alliance has a number of options. It could launch a sort of cavalry charge from Jabal Saraj, its forward headquarters, and try to reach Kabul, which is only 50 miles away. American bombers have heavily attacked Taliban positions at Kohi-i-Safi, 10 miles behind their front.

But there is only limited evidence, in the shape of a few deserters, that the Taliban is demoralised. In a drive south across the Shomali plain the Northern Alliance forces could suffer heavy casualties. Their supply lines are very long here, stretching all the way from Tajikistan three or four days drive away, and the Taliban's supply lines are short.

An attack on Kabul would also be a political mistake. It would anger Pakistan and irritate America. The Northern Alliance forces are ethnically Tajik on this front and their capture of the Afghan capital, repeating their success in 1992, might frighten the Pashtun, 38 per cent of Afghanistan's population. Dr Abdullah Abdullah, the Northern Alliance foreign minister, said at the weekend that his army might not send their main forces beyond the outskirts of the city.

But all this is very much dividing the Taliban tiger's skin not only before it is dead, but before it is even seriously wounded. So far the biggest blow to the Taliban has been the loss of its control of the air. This was important to them because it allowed them to move their troops to and from cities such as Mazar-i-Sharif and Kunduz in the far north. These forces are now isolated, apart from a single road. The Taliban has no way across the Hindu Kush mountains which divides Afghanistan.

The obvious strategy for the Northern Alliance is to try to take all of Afghanistan north of the Hindu Kush. This is a land of minorities all of whom have suffered at the Taliban's hands. To the north-east are the Tajiks in the great mountain fortress of the Panjshir valley. In central Afghanistan are the Hazara, reputedly descended from Genghis Khan's Mongols, who, as Shiah Muslims, have been persecuted, starved and massacred by the Taliban. Further north are the Uzbeks, who were badly defeated in the civil wars of the 1990s.

Big advances in the war in Afghanistan have in the past usually been the result of sudden defections by key leaders and warlords – usually in return for a substantial bribe. This enabled the Taliban to take Jalalabad in 1996, which in turn opened the doors of Kabul. The following year they took Mazar-i-Sharif after it was betrayed by a senior commander only to lose it in a general uprising against their rule.

Could the Taliban find themselves betrayed in turn? Afghan warlords do not like to bet on a loser. Money will presumably be available. But the Taliban will be on their guard against betrayal. In the past they have been notorious for not allowing commanders who have defected to them to have substantial influence.

How the Taliban can survive the cumulative military pressures on them is difficult to see. They no longer have the support of Pakistan and Saudi Arabia, which was so critical to their rise. Their many enemies at home scent blood. They alone, sustained by their fundamentalist beliefs, may not believe in the inevitability of their own defeat.