Last year in Libya an American drone identified and attacked the convoy Colonel Gaddafi was travelling in. A few hours later, after fleeing, he was caught by rebels and killed. And since the killing of Osama bin Laden, al-Qaeda’s top ranks have been eviscerated by drone strikes, culminating in June in the killing of Abu Yahya al-Libi, the al-Qaeda deputy in Pakistan. In military terms, their success is not in doubt. They have disrupted al-Qaeda by forcing its commanders to abandon telephones (drones can listen in on calls) and avoid meetings, communicating only by courier.

But drone strikes have also led to mass protests in Pakistan and spawned numerous campaigns against them. Do they really represent a new, sinister form of battle in which moral judgments are delegated to machines? And does their deadly accuracy ensure that 'collateral damage’ is minimised, protecting civilians in war zones? Or do they encourage trigger-happy pilots, free from risk in their cockpits on the ground?

Since 2007 the RAF has operated 39 Squadron, a detachment of five US-built MQ-9 Reaper aircraft at Kandahar Airfield. While America has a sprawling UAV programme targeting Islamic militants everywhere from Pakistan to Somalia, British Reapers have only ever been used as part of the official combat mission against the Taliban over Afghanistan.

The vast majority of the 38,500 hours of operations flown by the RAF Reapers have been in intelligence-gathering rather than in attacking targets. Most of the 35 RAF Reaper pilots are based at Creech, an airfield near Las Vegas, where they control the aircraft via satellite as they fly over Afghanistan.

_{An RAF Reaper drone in its shelter at Kandahar Airfield, Afghanistan, armed and ready for a mission (NEIL DUNRIDGE)}

But the two-second delay between a pilot moving a joystick in Nevada and an aircraft responding in Afghanistan is enough to cause a crash during take-off and landing. Crews in Afghanistan control 'launch and recovery’ through direct contact with antennae on the aircraft. Half an hour after take-off, control of the Reaper is handed to a crew in Nevada; half an hour before landing, it returns to the crews on the ground in Kandahar.

Kandahar Airfield is a vast, crowded military camp, full of private-security contractors in new SUVs, soccer pitches, traffic jams, and the 'boardwalk’ – a Midwest-style town square where soldiers carrying automatic weapons visit frozen-yogurt outlets and TGI Friday’s. Far from prying eyes, the Reaper pilots work in a corner of the airfield behind concrete blast barriers to protect them from the sporadic Taliban rocket attacks.

Their cockpit is a cabin full of wires and computer servers – a sealed and spotless world without the film of white dust that covers Kandahar Airfield. The crew sit side by side in leather seats as if in a conventional aircraft, dressed in all-in-one khaki flight suits. A technician fiddles with wires on a bank of hard drives. Office carpets cover the floor. Apart from the low rumble of the air-conditioning, it is as silent as a cathedral.

A black-and-white screen is filled with the featureless landscape of southern Afghanistan’s red desert. The conventional head-up display is superimposed on the screen, as in any fighter aircraft, giving the details of altitude and pitch that a pilot needs. But, unlike in a conventional aircraft, the pilot can switch the camera view in front of him to see behind or below. He manoeuvres the aircraft with a games console-style joystick. In front of the pilot is a keyboard, next to him a telephone. Reaper pilots can make telephone calls, or email photographs to operational commanders; they can go to the lavatory or get coffee during a flight.

A slogan among Reaper pilots is 'no comms, no bombs’: the system is wholly dependent on satellite links working. If there is an IT breakdown, the Reaper’s lost link’ program directs it to land at the nearest air base. Seated next to the pilot, the sensor operator controls a swivelling electronic eyeball on the nose of the Reaper, fitted with infrared sensors for night vision.

'We can say to troops on the ground, “Hey, we saw this guy run out of the compound – he’s hiding in the field,”’ Winston, an American former F-16 pilot who has moved to the Reaper, says. 'We can see headlights and engines that are hot from vehicles that have run recently. If a command wire has been placed across the road, the infrared will show the earth a different colour where it has been disturbed – and you can save a convoy from driving over an IED.’

Half an hour earlier, via Internet Relay Chat (a kind of instant messaging), the pilots took control back from the crews in Nevada at the end of a mission without a word being spoken. The word ready appeared on the screen in front of us, typed by the pilot in Creech. The pilot in front of us replied, ready. ours. Then yours flashed up on the screen, confirming the handover.

Tension fills the cabin as the pilot lines up the Reaper with the runway for landing. No speaking is allowed, since landing the aircraft, with its long, glider-style wings and lightweight body, requires concentration. Sandstorms and 60-knot crosswinds frequently buffet the aircraft, and the margin of error between a safe landing and a crash is only one degree of pitch. As the infrared outline of the hot tarmac looms into view on the pilot’s screen, there is no sense that the aircraft is descending, nor any jolt as the undercarriage retracts.

All the sensory instincts a pilot normally uses are missing; he is forced to fly by the instruments. Reaper pilots rely on forward-facing camera and see through the 'soda-straw’ view. As the Reaper nears the ground, the pilot calls out the altitude: '10, 9, 8, 7, 6…’ The only way we know he has landed is when the altitude reading on the head-up display is zero feet.

A short walk from the flight cabins are the mess rooms of the huge US Reconnaissance Force Reaper unit that shares facilities and operations with the RAF. On the wall are children’s paintings with messages to Daddy, and vintage Apocalypse Now posters. Small talk is of next week’s squadron barbecue. In this US military milieu, the RAF has colonised a corner with Union flag-covered lockers and photographs of the Duchess of Cambridge. More startling are the 1970s photographs of a thickly mustachioed Burt Reynolds, mirrored in the upper-lip growths of the airmen sitting drinking soda. (It is the end of 'Moustache March’, an annual USAF contest to grow facial hair for charity.)

^{An RAF Reaper pilot at Kandahar Airfield, Afghanistan, controls a Reaper drone, with the help of a sensor operator, to his right (NEIL DUNRIDGE)}

The RAF crews based at Creech take their place in a four-month rotation in the 'launch and recovery unit’ in Afghanistan. Sitting in the mess are Oz, a bald, middle-aged RAF Reaper pilot who has flown three tours of duty in the Tornado, and DJ, a former Royal Navy helicopter pilot. Both seem too grizzled to be described as PlayStation warriors. Like these two, all the RAF Reaper pilots have been trained to fly conventional aircraft, and most have fought in previous wars.

These pilots talk up the similarities with manned aircraft. Although they don’t suffer the exhausting effects of g-force and can’t look out of the window, they admit to flinching when they see something coming towards the aircraft.

'It’s irrelevant where you are physically sitting,’ Oz says. 'You’re attached to the airframe, you’re attached to the view that you see, and you’re attached to the laws of armed conflict.’

He reacts with cool anger to suggestions that this mode of war reduces victims to the status of players in a video game. 'It’s a bugbear of mine because I’ve had the accusation levelled that it’s a Star Wars game. It’s anything but. If we act like it’s Star Wars, there are people in the command centre watching us and listening to what we do. The taking of human life is not something to be considered lightly. OK, they are bad guys we are killing, but they are still human beings.’

He also bridles at the suggestion that UAVs leave moral judgments to machines. 'The plane cannot start, cannot fly and cannot release a weapon without us doing it. Human beings are in the cockpit – exactly the same as when I was flying a Tornado. We just happen to be 8,000 miles away from the plane.’

The courtly, upright American colonel in charge of Reaper operations, 'Ghost’, arrives, just back from the Kandahar military hospital, where he was visiting an American soldier shot in the leg on the battlefield. His Reapers provided 'overwatch’ while the soldier was evacuated by helicopter. It is common for the squadron to receive texts or emails of thanks from those they have protected. A group of Royal Marines made a trip to Las Vegas last year to thank the pilots in person.'We’ve had Humvees breaking down,’ Ghost says, 'and we’ve provided overwatch. You’re not going to get a good night’s sleep in the middle of the desert in Afghanistan normally, but if you’ve got a Reaper overhead that’s got your back, then you can.’

Afghanistan has been the ideal conflict for the Reaper. Unlike conventional fast-jets, which provide intelligence to troops on the ground only for short periods before having to refuel, the Reaper can stay in the air for 18 hours. It can stream real-time video feeds to troops for the duration of a skirmish, allowing them to see the Taliban’s positions on their laptops. And if they are required to fulfil their other major role, killing Taliban forces judged an immediate threat, they can circle for hours above a compound or a village, waiting for a confirmed sighting in the open of their target, before dispatching one of their laser-guided Hellfire missiles. These Taliban fighters won’t even know that they are being watched – at 15,000ft, Reapers usually fly too high to be seen or heard.

Stories spill out of the pilots. 'A British vehicle was disabled and the troops had to leave it,’ Oz says. 'The Taliban showed up in numbers. And we provided overwatch for them for hours while they [British troops] withdrew. They were able to withdraw without the fear of being overrun.’ Sometimes the threat of force isn’t enough, DJ says: 'We got called in because US Marines were under fire and were pinned down. We prosecuted [military jargon for 'killed’] two chaps. That broke their fire. The other four scampered, allowing the other Marines to withdraw.’

The Reaper pilots insist their high-resolution cameras, as well as the long periods that they can stay airborne, give them more time to weigh decisions before weapons are fired.

'On a fast-jet, because of the speed you’re coming in at, you don’t have the fuel and the time to hang around. But we can sit on top of this thing for hours at a time,’ Oz says. 'We have the luxury to pick up the phone and say, look – something just doesn’t look right here.’

This recently happened when the RAF Reaper pilots saw what they thought were Taliban insurgents preparing to fire. 'But something didn’t make sense. These guys seemed a bit too casual. So we checked for longer. As soon as these guys hit the road, they suddenly went into tactical column. We suddenly realised they were Afghan National Army. They weren’t the best-disciplined troops until their sergeant was looking at them. The luxury we have is that we can just sit there and say, we’ll just watch this for a few more minutes.’

The mantra that the Reaper pilots repeat is 'zero expectations of civilian casualties’. They are forbidden to attack buildings if there are women and children in the area and they avoid targeting property. In Afghanistan village life, Taliban fighters are never far away from women and children.

In internal reporting the RAF has dropped the term 'compound’ because it obscures the simple truth that these are houses. As one senior commander told me, 'We’re trying to get it into the guys’ heads that this is not compound no 28, it’s 34 Acacia Drive – so you don’t hit it.’

According to Oz, 'We’ll spend hours watching some guy. There have been plenty of times when I’ve had a clearly identified enemy combatant under my crosshairs and I haven’t been able to fire at him because he’s in a village and there are civilians around. If there’s any doubt, we won’t fire. Apart from the tragedy of wounding or killing an innocent civilian, it plays straight into the hands of the enemy for propaganda – it’s a double whammy. You have to wait for your opportunity.’

It is curious that civilian casualties from drone strikes receive so much attention, while those caused by conventional attack aircraft, whose pilots are also miles away from their targets, are overlooked. But this is because anti-drone campaigners doubt the MoD’s estimates of civilian casualties.

Reapers have, as of September this year, fired their weapons 319 times and killed four civilians in total since they started operating in Afghanistan, according to the MoD. These civilians died, along with two Taliban 'insurgents’, when two pick-up trucks carrying explosives were targeted by an RAF Reaper in Helmand. A military investigation concluded that this attack had been in accordance with correct procedures and UK rules of engagement.

Campaigners complain that the system for counting civilian casualties is flawed because it relies on villagers in remote parts of Afghanistan making the effort to report deaths to coalition forces. They also complain more generally about the secrecy around the Reaper programme, which fuels distrust. Only 40 per cent of drone strikes have been revealed in official RAF operational updates – the others remain classified. And there are no figures of how many 'insurgents’ have been killed (the deliberately vague term includes Taliban and al-Qaeda). The MoD attributes this to the need to not let their enemy know exactly how it is being targeted, and to difficulties in collecting information for an accurate body count.

The lengths of deployment for Reaper pilots, split between short stints in Kandahar and three years in Nevada, means that they have more experience of the war in Afghanistan than many of the soldiers on the ground. The terrain and the 'pattern of life’ in the villages they watch for suspicious changes become as familiar as those of their home towns. Often they observe a building for their whole shift and come back the next day to watch the same deserted building for another eight hours.

Does it get boring? Winston, the US Reaper pilot, admits, 'The honest answer is yes. You may get information that the unit is going into an area in three days and you’re told, “Don’t take your eyes off that building.” So you will fly in a circle for an eight-hour shift looking at it, and four hours in somebody walks in or walks out. You have no idea who it is. But somebody is watching the feed.’ (The audience for a drone feed can include troops on the ground, commanders in Afghanistan and intelligence analysts thousands of miles away.)

At times like this they find ways to relieve the boredom. 'You try and find humorous things. You see kids getting into fights and you’ll watch that, or traffic jams where some guy moves his goats across the road and people get upset.’ The stress of constant operations and long shifts, albeit with rest breaks, has led to fears of burnout among Reaper pilots. The almost limitless demand for 'overwatch’ creates a huge workload: every stream and every suspicious-looking building on a convoy route is checked for IEDs or a potential ambush by Reapers before troops go out on patrol.

The usual pattern of war fighting is to spend four months in a war-zone before returning home. But the Reaper pilots at their base in Nevada are commuter warriors: they work five days a week and drive home to their families at the end of their shifts. A tour of duty for them can last years. This changing tempo of war is taking a toll on pilots, even though they are not themselves in harm’s way. According to a survey by the Air Force School of Aerospace Medicine, nearly half the operators of UAVs have high levels of 'operational stress’ caused by long hours and extended tours of duty.

_{An RAF drone over Afghanistan, armed with two GBU-12 laser-guided bombs and four Hellfire missiles (CROWN COPYRIGHT)}

The RAF is moving some pilots from three years in Nevada back to three more years on operations in a new Reaper control centre in Britain, where they will also pilot Reapers over Afghanistan. According to a squadron leader with several years’ experience flying the Reaper, 'Six years of permanent ops is something that we’re going to have to pay great attention to. Chronic fatigue could become an issue.’ The effect on pilots of this strange new state of being simultaneously at home and at war has not yet been tested.

About four per cent of US UAV operators have developed post-traumatic stress disorder, which some have attributed to the fact that powerful cameras show close-up footage of the targets of drone strikes after they have been killed. 'The cameras are good,’ Oz says. 'A Hellfire missile does have significant effects on the human body, and you should get to see that. If you can’t accept it, you are in the wrong job. But the weirdest thing for me – with my background [as a fast-jet pilot] – is the concept of getting up in the morning, driving my kids to school and killing people. That does take a bit of getting used to. For the young guys or the newer guys, that can be an eye opener.’

At sunset at Kandahar we walk on to the flight line to see the angular, insect-like Reapers close up. Two of the RAF Reapers, distinguishable by RAF roundels, are being refuelled and armed with Hellfire laser-guided missiles before being sent out again, two hours after their last mission. 'This is only a small fraction of the Reapers we have here – the rest are in the air,’ Ghost says.

The Reapers are sleek, shark-grey and about the size of a light aircraft – 'a Cessna with a missile’, as some of the fast-jet pilots like to call them. They are so compact because they do not need systems to support a human: no air system, pilot’s instruments or ejector seat. If a Reaper is shot down or crashes, the taxpayer loses tens of millions, compared with the hundreds of millions that a conventional jet can cost. And they never risk a pilot being killed or captured.

As a Reaper taxis by, I ask the 39 Squadron pilots how they cope with the 'chair-force’ jibes that come from fighter pilots. 'They can say whatever the hell they like,’ DJ says, more than a little testily. 'This is the leading edge of combat. As time progresses there is going to be a bigger appetite for these airframes,’ Oz admits. 'Flying a fighter aircraft was more fun. It was big, it was pointy, it went bloody fast and it carried big bombs. It was sexy. Who wouldn’t want to do that? Twenty-five years later I asked to come to the Reaper because it makes a significant contribution to the war.’

A short drive in a battered Land Rover across Kandahar Airfield is the headquarters of 617 Squadron, 'The Dambusters’, which flies Tornado fast-jets over Afghanistan. In the mess-room, where a flat-screen television and piles of DVDs kill time when they are on call to 'scramble’, I ask the pilots whether they would give up their fast-jets for UAVs. With varying degrees of politeness, they decline: 'I’ve no interest in flying Reaper. If I’m flying I want to be airborne,’ one says. But could their jobs eventually be replaced by UAVs? 'Reaper is absolutely the asset for Afghanistan but as soon as you start going up against anyone with a credible air threat we will have to pour money into aircraft that can fight back.’

It is a frequent criticism that Reapers work well in Afghanistan, where there is no air force and no accurate surface-to-air missiles, but in a conventional war these slow, fragile aircraft would be easy to shoot down. Though fast-jets such as the Tornado cannot stay airborne for as long, they can travel long distances more quickly. If troops are under fire at the far side of Afghanistan, the battle is likely to be over long before a Reaper arrives on the scene. Nor would Reapers fare well in colder, wetter weather.

Already the high rate of UAVs is a matter of concern to military planners. Figures are difficult to verify, but the UK Drone Wars website, run by anti-drone campaigners and using imperfect information, has recorded 14 drone crashes so far in 2012. The Los Angeles Times estimated in 2010 that 38 Reaper and Predator UAVs had been lost in Afghanistan and Iraq.

During the Balkan Wars, experiments with UAVs were abandoned because so many were lost in the bad weather. Fast-jet pilots argue that a crew in the air above the target can always make better judgments than a crew thousands of miles away. 'We can give more an interpretation of what’s going on,’ a Tornado flight commander says. 'It’s hard to put into words, but there is just that feeling of being there. You can see the whole situation and not just the target. The fact that you can look out of a cockpit and say, “There’s a village next to us.” We could be talked into thinking that a couple of men kneeling in the middle of the road at night look dodgy when it’s actually a guy changing a motorbike tyre that’s just had a puncture.’

Whatever the counter-claims between Reaper and fast-jet pilots, the arguments in favour of UAVs have been won in the Ministry of Defence. Later this year a new squadron will be established in Lincolnshire to pilot remotely five more Reapers – the first time that drone missions in Afghanistan will be been controlled from British rather than American soil. However, there are practical difficulties to overcome first. It remains unclear where the UK Reapers will be legally able to take off and land when combat operations end in Afghanistan in 2014. Civil Aviation Regulations prevent them from flying in British airspace since reaction times might not be fast enough to avoid collisions.

By 2030, the RAF estimates, a third of the force will be unmanned aircraft. An MoD report, 'The UK Approach to Unmanned Aircraft Systems’, predicts, 'Unmanned aircraft will eventually take over most or all the tasks currently undertaken by manned systems.’ The expensive F35B Lightning II fighter currently on order will be, it predicts, the last RAF fighter with a pilot in the air.

The UAV technology under development sounds like science fiction – from bee-size nano drones that can fly through windows to nuclear-powered drones that can fly for weeks without refuelling. Even if these wilder plans never see the light of day, the MoD has been funding the development of Taranis, a long-range jet-powered UAV attack aircraft that will be able to fly across continents.

The moral question overshadowing UAVs is whether their use trivialises the business of killing. According to the report 'Armed Drones and the PlayStation Mentality’ by Chris Cole, the director of the Drone Wars website, 'Young military personnel raised on a diet of video games now kill real people remotely using joysticks. Far removed from the human consequences of their actions, how will this generation of fighters value the right to life?’

From my experience at Kandahar this vision of teenage warriors seems far-fetched: the Reaper pilots I met were approaching middle age, softly spoken and sober about the life-and-death decisions with which they were charged.

It does, however, seem plausible that risk-free, long-distance strikes using UAVs could insulate the Western public from the human toll of war. If we can kill with such ease while protecting Western lives and avoiding the costs of deploying troops, will the bar be lower for governments to make war? Already, the creep towards a permanent state of war, via drone strike, can be seen. This year alone, the Obama administration has conducted drone strikes against al-Qaeda and its allies in Afghanistan, Libya, Yemen, Pakistan and Somalia. The Ministry of Defence candidly warns of these dangers in its report: 'We must ensure that by removing some of the horror, or at least keeping it at a distance, we do not risk losing our controlling humanity and make war more likely.’

These speculations become even more complex with the Frankenstein fear that, as UAVs become more advanced, they will be able to launch weapons without human input. There is a danger of an 'incremental and involuntary journey towards a Terminator-like reality’, the paper warns, and Britain must 'quickly establish a policy on what will constitute “acceptable machine behaviour”’.

Drones deliver death out of a clear blue sky. Victims will not have known their fate for more than a fraction of a second. Most of the time they won’t even have heard the Reaper’s engine. Is it possible such powerful weapons will hand a propaganda victory to those they are targeted against?

At some point military planners will have to face these issues. But, for the moment, the public is more likely to be swayed by the belief, shared by everyone on the ground in Afghanistan, that the Reaper has saved the lives of hundreds of British troops.

For the pilots, misgivings over a new weapon changing the nature of war are nothing new. On the flight line in Kandahar, DJ has to shout over the whine of a fully loaded Reaper about to take off for another long mission. He is dismissive of the angst surrounding unmanned aircraft. 'This goes back centuries. When it was sword versus sword and somebody started slinging an arrow over their head to the enemy – every time there’s an advance in military hardware, the other side says, “Are you playing fair?”’