Under the steady thumping of rotors, the French Caracal and American Pave Hawk helicopters race off towards the snow-covered French Pyrenees.

The location is well-chosen: the southern French mountains resemble the rough landscape troops will face in Afghanistan. Here, both countries' troops can get used to working together on their mission to stabilise the country.

"The terrain is incredible here -- it's very realistic to Afghanistan," said the commander of the US contingent, Lieutenant Colonel Neil Eisen. "We can get the realistic conditions, terrain and altitude, for trying to land in Afghanistan."

The 56th Rescue Squadron of the US Air Force in Europe has joined its French counterparts, the Pyrenees Helicopter Squadron and a French parachutist commando unit for the exercise, code-named Red Devil.

Officers involved said the US forces' visit to southwest France marks the first time a US combat rescue squadron has been invited to train on French soil since then-president Charles de Gaulle asked US forces there to leave in 1960.

The US squadron, recently home from Iraq and based in England, has brought three helicopters, two planes and 85 troops, including 20 Pave Hawk pilots and a team of elite parajumpers, for three weeks of pre-combat training.

In Afghanistan, all of the soldiers involved in Red Devil will share a similar mission: rescuing their comrades and providing emergency medical treatment for the injured in hostile areas.

"We rescue anybody -- from a fighter pilot who punches out, to marines on the ground," said Master Sergeant Louis Distelzweig, recently returned from Iraq, and a veteran of seven tours in Afghanistan during his 21-year career as a "para-rescuer".

As more American troops pour into Afghanistan, more joint missions with the French troops who form part of the US- and NATO-led international security force there are a certainty.

"We are in the same theatre, same mission, under the same commander -- so I'm quite sure we will be engaged in the same conflicts," said the French commander for Red Devil, Lieutenant Colonel Olivier Celo.

"With the conflicts increasing, as soon as you have more people on the ground, more fights on the ground, more injured soldiers, we'll have to evacuate more people."

With the Americans at Bagram airbase and the French just "down the road" at the Kabul airport, "there are times when we are flying in the exact same zone," said Eisen.

"It won't be planned -- it will simply just happen," he explained. "And when we're down range, there aren't any Americans, any English, any French, we're all together, so why shouldn't we train that way?"

Joint missions, however, create new risks. "It would be detrimental for the French and Americans to work together on a real-world war mission, unless they work together here and both learn each other's language," said Distelzweig.

"The challenge is the language barrier and different tactics and techniques," said Eisen. "The reason we are training together is to figure out how to work out those differences now, before we go into combat."

The major draw for the Americans is the unique topography of the French training ground: sand and dust landings, rugged mountains, and snow.

The French for their part get to learn about aerial refueling, a capability only recently available to them with the addition of the Caracal to their fleet.

The Americans brought along two MC-130P Hercules tanker aircraft and members of the 67th Special Operations Squadron, which specialises in clandestine aerial refueling.

The US forces also "have a certain technique for disembarking commandos, and tactics for flying and low-altitude penetration," according to Lieutenant Colonel Fabrice Albrecht, second in command of the French squadron.

"The objective is to share that on the terrain."

Pilots and parachutists were keen for the joint training.

"When we work with the French, we can see how the helicopters react, how we communicate as a crew and how we do close-flight approaches," said pilot Marisa Caitlin, after her training flight.

The Americans also learned a new tactic for "emergency extractions", a technique not previously used by US para-rescuers.

It involves "120 feet of rope hanging from the helicopter and 10 guys hooked in at the bottom while the helicopter flies to a safer spot to land," said Distelzweig.

Both countries' troops face a tough fight against the Taliban forces in Afghanistan, undertaking extreme missions under fire.

Under Celo's command -- and with the participation of US forces -- the French squadron distinguished itself during the rescue of ambushed French forces in Ouzbin in August 2008.

The fight left 10 French soldiers dead and many wounded. The squadron evacuated 89 people.

Training operations like Red Devil leave both forces better prepared to respond to the harsh conditions awaiting them in Afghanistan. Already both sides have said they want to schedule more joint training sessions.

"Conflicts have evolved. Yesterday, we were in symmetrical conflicts, two states against one another. Today we are in asymmetrical conflicts -- counter-insurgency war," explained Albrecht.

"We have to change our tactics."