When the US withdraws many of its troops from Afghanistan in 2006, Nato forces will take over in areas of the country where they can expect far tougher challenges than they face at the moment. Paul Adams spent a week with a Nato general to get a closer look at the problems that may lie ahead.
The Nato force is drawn from more than 30 countries
The general leaned forward and peered out of the cockpit of his Hercules, his gaze resting on the endless, rolling ridges of dun-coloured hills.
As he looked at this apparently desolate landscape, I wondered what thoughts were going through his mind.
General Gerhard Back - former fighter pilot and head of the German air force - is the man with operational control of Nato's presence in Afghanistan.
That presence, limited to a few thousand troops in a handful of locations, is now expanding. And with expansion comes responsibility and danger.
It was a big step for Nato to come here at all. But the coming months will test the resolve of an organisation that has a hard time living up to its own expectations.
After visiting Kabul, where Nato first got its boots on the ground, and Herat in the west, where Italian and Spanish troops are only just settling in, our journey took us to Kandahar, close to the front line in Washington's so-called war on terror.
It is a huge, dusty base which sprawls across the southern plain, a short helicopter ride away from the caves that perforate the mountains along the Pakistani border.
It is from here that the United States supports its combat troops in their forward operating bases.
Finishing the job
And while we in Britain do not seem to hear much about this war any more, let me tell you that the skies above Kandahar are alive with men and machines, attempting to finish what they came here to do.
Great lumbering C-17 transport planes fly in direct from Germany, carrying all manner of equipment.
The air reverberates to the sound of helicopters. And everywhere soldiers and civilian contractors tramp about in wraparound shades, getting on with their business. Which is, in short, to destroy what is left of the Taleban.
And they think they are winning.
Since the end of a particularly harsh winter, the Americans have been going after their opponents with renewed vigour, hoping to finish them off once and for all.
"They're showing their teeth and we're showing ours," an attack pilot, Alexander Swyryn, told me.
And the result? By the end of the summer, he said, almost diffidently, most of them would be either killed or captured.
It is easy to talk, of course, but all over the base I sensed that the Americans really believe they are reaching the end.
As we toured the facilities, General Back's eye was caught by the strange spectacle of a fleet of ghostly unmanned planes known as Predators.
Up to 800 Predators are said to be operating in Iraq and Afghanistan
These are flimsy, improbable machines that can monitor the ground by day and by night, eavesdrop on phone calls, fire missiles and stay aloft for almost 24 hours.
Oh, and they are piloted by someone sitting more than 7,500 miles away in Nevada. A useful bit of kit if you're looking for an enemy in the remote, rocky mountains of Afghanistan.
The general was clearly wondering whether he could have some and fell into conversation with a burly, moustachioed contractor who seemed only too happy to oblige.
He had the polished patter of the best used car salesmen but, as the conversation strayed into matters of capability and contracts, he and the general drifted away.
This was not for our ears. It was sensitive stuff.
As the Americans reduce their presence in Afghanistan next year, handing over more and more of their combat responsibilities to Nato, they will inevitably take a lot of their favourite toys with them.
Nato does not have the same kinds of capabilities.
And since this is hardly a secret, it seems reasonable to assume that any Taleban fighters left after this new offensive may choose to lie low and bide their time; wait for an altogether less intimidating opponent to take the field.
General Back told me he was confident. In spending millions of dollars on the Kandahar base, he said, the Americans had prepared a nice nest for Nato.
But he did not tell me whether he had done a deal on the Predators.
The burly contractor did not let on either but, when he told me what they could do, I almost felt he was trying to flog me one.
This man was not just a salesman, he was an evangelist.
"They help us all," he said, as he put his fleet of strange machines to bed in their hangar. "They help us all in the free world."
After three days of criss-crossing the country, General Back headed home to his Nato headquarters in the Netherlands.
Difficult months of discussion lie ahead.
Will Nato members be willing to change their rules of engagement to allow them to fight the way the Americans have?
Will the perennial problem of so-called "national caveats" prevent some countries from getting involved in dirtier, more dangerous work?
Germany, for one, will not send troops to the south. Britain is among a handful of countries that will.
And will the alliance be able to stump up the troops and equipment needed for such an enlarged undertaking?
Lots of questions for General Back to ponder as the battle-scarred landscape of Afghanistan slid away beneath us.
From Our Own Correspondent was broadcast on Saturday, 28 May, 2005 at 1100 BST on BBC Radio 4. Please check the programme schedules for World Service transmission times.