Marines wait for orders while politicians argue

The soldiers were meant to be the advance unit of a force at least 2,000 strong, an overt symbol of British martial presence in Afghanistan and a testimony to the diplomatic skills of Tony Blair.

On Monday, though, the 120 men from the Royal Marines Special Boat Service were spending a fifth night at Bagram air base, lightly armed and with no sign of the reinforcements of paratroops and marines they had been expecting to arrive by yesterday morning.

Surrounding them are about 2,500 fighters of the Northern Alliance, supposed allies in the war, who are opposed to the large-scale presence of British or any other foreign forces in the country. Their deputy chief of intelligence, Engineer Arif, has demanded that not only should there be no more troops, the number at Bagram should be reduced to 15.

Beyond them, in the hills, are the Taliban and al-Qa'ida, which would both like nothing better than a spectacular strike against Western forces; all they need is for one suicide bomber to reach the British garrison.

The SBS are finding that in the convoluted realpolitik of Afghanistan it is difficult to tell between friend and foe. The American special forces and intelligence agents acting as advisers to the Alliance are unhappy at the prospect of a large-scale British force on the ground. In fact, there is now increasing suspicion in London that, behind the scenes, the US had been fuelling the Alliance antipathy to the British.

The Allies have always had their eyes on Bagram. The all-weather air base was built by the Russians and became a crucial centre in their 10-year Afghan intervention. The air base has other advantages, a surrounding ridge providing natural protection; the longest runways in Afghanistan; and proximity to Kabul, 22 miles away, and routes to the city.

But the marines will also see the signs of how a previous advanced military plan – that of Moscow – did not run according to plan in Afghanistan. The hangars, with shell holes and roofs torn off, house skeletal rows of damaged Soviet strike aircraft and helicopters, shot down by the Taliban with the Stinger missiles supplied by the US and distributed with the help of MI6.

There are also signs of more recent danger. The runways are cratered, and ammunition and shrapnel crunch beneath the feet. Beyond, the ground is heavily mined, providing another obstacle to troops venturing away from the base.

The control tower is badly shot up but the British troops already have it ready for incoming flights. But there has been no fleet of Hercules transporters bearing marines and paratroops, armoured vehicles, engineers, signallers and medics. Instead, there has been one aircraft, carrying Stephen Evans, Mr Blair's new ambassador to Afghanistan, and a group of Whitehall officials on their way to Kabul to persuade the Alliance that the British mean no harm.

The SBS, a squadron from Poole in Dorset, are successors to the "Cockleshell Heroes" who blew up a naval shipyard in Bordeaux during the Second World War using divers and limpet mines. To find them so far into a landlocked country is unusual; normally their operations would take place up to a dozen miles inland.

But their motto is: "Not by strength but guile", and they have built up a reputation as calm and level-headed – the ideal qualifications for such a delicate task. The troops can subsist for up to three weeks on their services' issue of Lancashire hotpot and Irish stew, chicken korma and beef casserole. After that, they will need fresh supplies, which will have to be procured and brought in with Alliance help.

They have taken up residence at a number of stone buildings towards the centre of the base, near the radar dish they have erected. There are perimeter sentries and regular patrols. The unit is making routine calls to pass on information and receive orders to Permanent Joint Headquarters at Northwood, London, via a signalling station in Cyprus. Their mood is said to be upbeat, if intrigued by what the plan is.

The Northern Alliance, according to military sources, has its own tactics. In the last century, the British and the Russians manipulated the Afghans for their own "Great Game", but the Afghans also played off one power against the other. Now, Alliance commanders are telling the British that their US advisers have said there are no plans to set up a large-scale coalition force on the ground, so what's all this about thousands of British troops?

As to the notion that they are for humanitarian aid, the UN says there is no problem in bringing in food and medicine now and the bazaars of Kabul are groaning with goods.

The marines on the ground would be even more confused if they were keeping track of what was going on in Washington and London. No clear definition of the task ahead has been given by Downing Street to the British commanders. That, say defence sources, is because Number 10 has not been told by Washington.

For the Government to accept the scenario of marching the troops up the hill, only to march them down again, is almost unthinkable. So a deployment will take place sooner rather than later. "Our mission", said a bemused commander "appears to be to prepare for a mission, whatever that is."