The aim is to pass responsibility over to Afghan forces as soon as possible
By Frank Gardner
BBC News, security correspondent
Control of the most dangerous region of Afghanistan for foreign troops is being handed over from British to US forces, but at the same time Afghan soldiers are being trained to take on the same kind of challenges in the future.
"Check your arcs and look to your front. Stay sharp."
The short, clipped commands from a British colour sergeant echoed off the mud walls of The Mount, a brand new Afghan army training centre, donated by Britain and just opened this week.
Another batch of Afghan recruits was being taught the most important skills of all - how to find and destroy a roadside bomb, before it blows your legs off
The Afghan soldiers looked on expectantly, squinting up at this pink-faced, tattooed Scotsman who had come from so far away to help teach them how to fight.
On a given signal, they burst through the gates, shouting and shooting blanks, clearing the empty rooms one by one.
Several of them were laughing, as if it were all a game.
The unseen enemy
But on the other side of this sprawling camp, shimmering in the desert plains just south of Kandahar, another batch of Afghan recruits was being taught the most important skills of all - how to find and destroy a roadside bomb, before it blows your legs off.
The UK government wants its troops out of Afghanistan by 2015
Lying half-concealed in the sun-baked mud was a rusting artillery shell, sinister wires trailing away from it.
"This," said the instructor, "is your unseen enemy. You need to pay attention."
There were no smiles and laughter here, just nervous glances. These Afghans had all volunteered to become bomb disposal specialists. The job carries extra pay and promotion.
But when they return to their front-line units in a few weeks' time, they know that many of them will be called on to do this job, that nobody else wants to do.
This is all part of what Western governments are calling "transition", the accelerated drive to train up Afghan security forces and hand over responsibility to them as quickly as possible.
'Sigh of relief'
The clock of Western public patience for this mission is ticking ever louder now. Already some nations are shuffling towards the door.
Next month the Dutch army leaves and next year Canada is due to pull out.
Increasingly, the Americans are having to fill in the gaps left behind.
The announcement this week that Britain would hand over its base in Sangin to US Marines draws a wry smile from some British soldiers.
Officially it is all part of a grand realignment of Nato forces in Helmand province. And it is true that it makes no sense to keep a remote British base up in the US task force in the north, when they could join up with the rest of their countrymen further south.
But privately, British soldiers are breathing a huge sigh of relief, knowing they are handing over to America something of a poisoned chalice.
Sangin's fanatical snipers and roadside bombs have killed at least 100 Britons since forces moved in there four years ago.
On top of a volatile mix of feuding tribes came an unpopular district governor, who had to be replaced earlier this year.
Sangin's bazaar may be open for business and infrastructure projects may be under way, but the fundamental problem remains unsolved.
Many in the local population there have not been persuaded to throw in their lot with the government, instead of with the insurgents and drug runners.
"Good luck to the Americans," said one British officer. "I don't envy them taking over that place."
It is all very different to life here at Nato's southern Afghan headquarters on Kandahar's massive airbase.
As the old Vietnam War saying goes, those serving their time here are "in the rear, with the gear, where there is no fear".
Like a newborn calf struggling to stand up on its feet, Afghanistan's army and police are still a very long way from being able to look after themselves
But actually that is not quite true.
Rudely disrupting the rhythm of camp life, the Taliban mounted a brazen assault on the base in May.
They fired a salvo of Soviet-era rockets and hurled themselves at the perimeter, having to be beaten back by helicopter gunships and a quick-reaction team on the ground.
The insurgents failed to get in or to kill any coalition troops, but they did not need to, to make their point: that they are not giving up until foreign forces leave and nowhere here is completely safe from their attacks.
"They'll try again, no doubt about it," said a US Marine Corps colonel. "This place is just too tempting a target."
Fledgling air force
Order restored, the base is back to normal and now everyone is grumbling about a new menace.
"Those blasted F18s," cursed one officer, referring to the US Marine attack jets whose pilots delight in flying very fast and very low over the camp, Top Gun-style.
Arching through the cloudless sky in pairs, their twin tail fins glinting in the sun, the planes make a terrifying low whistle, sounding so much like an incoming rocket that even the seasoned Dutch air force fighter pilots have been known to dive for cover.
Mostly they are flying surveillance missions, searching for roadside bombs from the air.
Afghanistan's fledgling air force is light years away from this sort of hi-tech mission. Even finding enough pilots who can read is still a challenge.
That is why, long after Nato's ground troops have departed, there will probably still be coalition airbases like this one.
Despite all the talk of transition to Afghan forces, the trainers' work is far from done.
Like a newborn calf struggling to stand up on its feet, Afghanistan's army and police are still a very long way from being able to look after themselves.
[photographs taken by Frank Gardner]
How to listen to: From our own Correspondent
Radio 4: Saturdays, 1130. Second weekly edition on Thursdays, 1100 (some weeks only)
World Service: See programme schedules
Story by story at the