AN elite British unit is preparing to join the hunt for Osama bin Laden in the mountains of northern Afghanistan, shattering the myth that the onset of winter will stall military operations.
The first snows are expected by the end of the month, bringing fierce storms, near-zero visibility and temperatures as low as -20C.
It is, historically, when warring Afghan factions lay down their arms and, say many commentators, Western troops will have to suspend their hunt until the spring.
But the 24-strong Brigade Patrol Troop is specialised in the extremes of winter warfare and could be the force on which the hunt for the Al-Queda leader and his men may ultimately turn.
The troop's talents include long-range reconnaissance, covert intelligence-gathering and hitting enemy targets under the most extreme conditions.
Recruited almost exclusively from the Royal Marine Commandos, they practise and refine their skills in the expanses of northern Norway.
The troop, based in Plymouth, comprises six four-man teams, each with a medic, signaller, sniper and patrol commander. All are parachutists and their weapons of choice are the M16 assault rifle or the L96 infantry sniper rifle, but at least one will have a Belgian Minimi light machine gun, which has a better rate of fire. They may also carry anti-tank weapons.
During the Cold War, they were used alongside regular Royal Marine Commandos as the first line of defence for Nato's northern flank against a Soviet invasion. They pride themselves on their ability to operate in weather conditions considered extreme even by the standards of special forces.
They have no equivalent in the US armed forces, and such are the selection standards that only a handful of SAS troopers have managed to join their ranks.
The men must be able to live in snow holes for weeks on end as they seek, and then destroy, the enemy. Their other skills include laser target indication for air attacks, ice wall and mountain climbing, resistance to interrogation and escape techniques.
As intelligence on the dispositions of the Taliban and the whereabouts of bin Laden arrives at US Central Command in Tampa, Florida, and the Joint Force Headquarters in Britain, the men will be inserted by helicopter to cover the high passes that al-Qaeda may use to move into lower valleys, where weather conditions are less hostile.
On arrival at their landing sites, the commandos will establish a ring of covert observation posts dug deep into the snow. From here, they will observe any movements and, with encrypted signals sent in high-speed bursts, report to their commanders at forward bases in Afghanistan or neighbouring countries such as Pakistan or Uzbekistan.
Their task will be to reconnoitre and observe possible routes, supply lines and secret locations so more heavily armed special forces troops, such as the SAS, can be flown in to intercept. But if they identify bin Laden or any of his lieutenants, they will be cleared to open fire.
The advantage of having a sniper in each section means the enemy can be engaged at a range of more than 3,000ft. Despite the noise, the echo should make identification of the firing point almost impossible.
Alternatively, if an al-Qaeda camp is located, the information they provide will allow planners to bring spy satellites on line, allowing the mountain troops to call in air strikes using conventional satellite and laser-guided bombs, or cruise missiles.
One military officer said: "We really are talking about a very special group of soldiers." The size of the troop reflected its special nature and the rigours of the selection process.
He added: "Their military skills must be exemplary and they must have bucketloads of mental stamina. They can expect to work behind enemy lines in atrocious weather conditions for weeks on end. That requires very special skills."
The onset of winter will also make it easier for spy satellites to catch sight of bin Laden and his men. Supply trails through the snow will be spotted, allowing planners to send in helicopter-borne troops or call in air attacks.