Throughout history, some forms of war and weaponry have been viewed with greater horror than others. Even ancient civilisations tried to codify the rules of war – jus in bello. Homer's Greeks disapproved of archery; real men fought hand-to-hand, not at a distance. Shakespeare's Henry V roared with anger when, at Agincourt, the French cavalry killed his camp followers. At the beginning of the last century, dum-dum bullets, a British invention, were outlawed following an appeal by Germany. Revulsion against the widespread use of gas in the first world war led in the 1920s to an international convention prohibiting the use of chemical and biological weapons – not that the ban stopped the British using chemicals in Iraq, or the Italians in Ethiopia in the 1930s. A landmine convention was agreed in 1997, though not signed by the US, China or Russia. Today, China, India, and perhaps surprisingly North Korea are among nuclear?armed states that have pledged no first use, though Nato, Israel and the US have not.

Other, equally horrific weapons go unchallenged. Napalm (invented on the playing fields of Harvard University), incendiaries, "daisy cutters", depleted uranium, defoliants … the list goes on and on. And the nature of war has changed. Warfare has become asymmetric; hi-tech states fight not each other, but shadowy insurgents, terrorists and freedom fighters. Where once the ratio of soldier to civilian war deaths was 9:1, now it has reversed. Today's hi-tech warfighters are at less risk than the civilians in whose territories they fight. The lives of each of these warfighters is precious: the US and UK mourn each of their few dead in Iraq or Afghanistan almost more intensely than they did the tens of thousands who died in 1939-45. To minimise such deaths, and to exploit developing computer and information technologies, the Vietnam war ushered in something called "the automated battlefield".

Enter the drones. As Medea Benjamin's well-researched book points out, speculation about the potential of autonomous flying vehicles long predates their actual construction. But in the modern era we have to thank above all Abraham Karem, chief designer for the Israeli airforce, who migrated to California and by the 1980s was building drones in his garage with the enthusiastic support of the US Defense Advanced Research Projects Agency and, later, the CIA. From then on, powered by huge advances in information and computer technology, drones have become irresistibly attractive to military and police forces across the industrialised world, providing a financial bonanza for the – mainly US and Israeli – companies that build them.

Today, drones range from the tiny humming-bird sized surveillance devices to the plane-sized Predators and Reapers carrying Hellfire missiles. "Gorgon Stare" drones can spy on an entire small city. Miniaturisation promises solar-powered insect-sized drones capable of staying aloft indefinitely or being steered into buildings to spy or kill. Drones have spun off from the military and are now used commercially in various ways, from delivering packages to spraying pesticides. You can buy your own smartphone-controlled drone from Amazon for as little as $300. There's no technical reason why they shouldn't in future replace pilots on passenger planes. And as always, there's an enthusiastic community of DIYers building and flying their own.

But it is their military use that is the focus of Benjamin's book. Initially, they were used primarily for surveillance; by 2003, US drones were logging 1500 hours a month in Iraq; and by 2010, 20 Predator flights were providing some 500 hours of video surveillance a day in Afghanistan. They were limited in their use during the George W Bush presidency, but Barack Obama initiated a step?change by approving their use for "targeted killing", not just in Afghanistan but also Pakistan, an escalation already pioneered by the Israelis in Gaza. The drones track and kill identified militants – or individuals whose behaviour, as observed from the drone, fits a pattern thought to typify militancy. Despite numerous direct reports of civilian deaths, the Obama administration insists that so-called collateral damage is slight. However, as it also persists with the view that any prime-age male killed by a drone is by definition a militant, the claim lacks elementary credibility. Even the anger over the deliberate targeting by the CIA of a US citizen in Yemen in 2011, or the accidental killing of 20 Pakistani soldiers in Waziristan has not limited their use. A recent British poll found 54% were in favour of such targeted killing.

That such extra-judicial killing is illegal is not in doubt – as has recently been reconfirmed by the UN special rapporteur Ben Emmerson. Obama's justification is similar to Bush's – that those killed are actively threatening the security of the US. But the crucial issue is an ethical one: the pilot of a drone tracking the movements of a Waziri villager and making a life-or-death decision to fire a missile may be sitting in a control room in a US air base in the Nevada desert. That's when many will agree with Benjamin, a founder of the women's anti-war movement CODEPINK, that a moral line has been crossed.

Is firing a missile from a drone morally worse than dropping a 500lb bomb from 10,000ft? Or pressing the button that launches a cruise missile? Perhaps what is repugnant is the unique combination of deliberately firing at a specific individual, combined with distance and the knowledge that you yourself are invulnerable to retaliation. Time to reprise the ancient Greeks with their contempt for archers. Despite some loose editing and repetition, Drone Warfare is both a justifiably angry sourcebook and a call to action for the growing worldwide citizen opposition to the drones.

Steven Rose is the co-author, with Hilary Rose, of Genes, Cells and Brains. 

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