The Government is anxious to avoid the description "mission creep" and the military commanders say they have not been given an exact description of what their mission will be. But, with 4,000 paratroopers and marines on stand-by, Britain is now likely to have the biggest foreign involvement in the Afghan land war.
Although the United States, very much the senior partner in the war, already has about 3,000 troops in Uzbekistan, Washington has been conspicuously quiet about deployment in the volatile and rapidly changing situation on the ground and there is deep antipathy there to getting involved in a policing operation.
The new forces will augment the 4,200 already deployed, including a battle fleet led by the carrier HMS Illustrious and 238 Royal marines, with another 400 ready to join them.
The composition of the troops certainly indicates that there is a prospect of combat – the 3 Commando and 16 Air Assault Brigades, including the 2nd Battalion, the Parachute Regiment, and 45 Commando Royal Marines. In addition, there will be engineers, bomb disposal squads and logistical support, and RAF Hercules transport aircraft and helicopters to fly them into Afghanistan.
The deployment, according to senior military and diplomatic officials, is very much in keeping with the Prime Minister's desire to show the leading role that Britain is playing and will play, a natural denouement to his high-profile shuttle diplomacy. By necessity this means not just the secret missions being undertaken by the special forces – SAS and SBS--inside Afghanistan, but also an overt presence.
But there were elements of confusion about the mission. The Ministry of Defence's initial statement said "there is no intention to deploy these forces in offensive operations against the Taliban". This was later changed to "we are keeping all our options open" by a senior official, and Downing Street gave a particularly gung-ho briefing.
A senior officer said yesterday: "I wouldn't describe it as a force, but rather a menu of capabilities from which we can dine à la carte." The Ministry of Defence statement, however, had no such ambiguity: this was the "UK Joint Rapid Reaction Force".
The various units have been put on a "reduced notice to move" as of 6am yesterday morning. This means that, technically, they should be ready to be deployed by 6am on Saturday. The exact nature of their mission has not been specified, but they appear to fall into a mixture of helping to provide humanitarian aid, policing, and military operations.
The initial contingent, including C-130 Hercules and C-17 Globemaster transport aircraft, is expected to land at the all-weather Bagram airport, north of Kabul, once it has been made ready. The aircraft may make refuelling stops in Oman in the Gulf, the former Russian bases in Uzbekistan, or western Pakistan.
Bagram, which was built by the Russians during their intervention, has remained relatively undamaged in the civil war and has a natural defence line of ridges all around. The engineers and logistics personnel will, however, have to carry out essential work at Bagram to secure it and make it ready for the heavy traffic expected.
But logistically, Bagram alone is far from ideal, because of the size of Afghanistan. Ideally, the allies would like to establish bridgeheads in the southern airports at Kandahar and Lashkar Gah, Jalalabad in the east, and Herat in the west. The southern ones are yet to be fully wrested from the Taliban and all of them need various degrees of repair.
With the Taliban threatening to launch a prolonged guerrilla war from the hills, the role of the marines' 3 Commando brigade will be, potentially, of great importance. The 238 on board HMS Fearless, and another 400 who are expected to join them, are specialists in mountain warfare and have been training for the Afghan mission ever since they finished Operation Saif Sareea II in Oman two weeks ago.The paratroopers of the 2nd Battalion are more likely to be used in combat, if necessary, in the arid and flat Pashtun heartland of the south.
The military planners have yet to establish whether the various allied forces likely to appear in Afghanistan--the US, Britain, France, Turkey, Australia, Italy, Germany, and so on --will have their own zones, as in Kosovo.
Britain's Chief of Defence Staff, Admiral Sir Michael Boyce, had stated that the British operations would be autonomous. However, that was before the latest large-scale reinforcement.
So far, no commander has been appointed, although the 3 Commando Brigade is run by Brigadier Roger Lane of the Royal Marines. Brigadier Lane has been in the news for warning forcefully during Operation Said Sareea II against premature action and stressing the need for clear targets. "We don't want to be hasty, we want to be right," he said.
Those units not involved in fighting the remnants of the Taliban or trying to capture Osama bin Laden and his al-Qa'ida network will be deployed in areas now under Northern Alliance control, including the main centres of Kabul, Herat, Jalalabad, and, once it is captured, Kandahar.
One of their main roles will be to ensure that the Northern Alliance do not take revenge on former Taliban supporters and ethnic Pashtuns. As the takeover of Kabul shows, however, the Alliance will not be bound by the wishes of Washington and London, and their intentions are uncertain. A senior British military officer admitted yesterday: "We don't know what they are going to do."
Senior commanders have stressed that there will be no move to supplant the Alliance. Instead, there will be close liaison with individual commanders and attempts to cater for their logistical needs.
Britain and the European Nato allies are keen to pursue a hearts-and-minds campaign and policing will be accompanied by the distribution of aid, not just to the civilian population, but Northern Alliance forces as well. Publicising this would, it is felt, help counter the unpopularity of military action in the Muslim world.
British commanders also see the role of the forces as smoothing the way for the United Nations and the future non-partisan government of Afghanistan. And at that point they want to leave before they are sucked into an Afghan quagmire.
That is the ideal scenario. But as the last few days have shown, events tend to overtake the West's plans in Afghanistan, and the future course of British involvement is far from certain.