The ancient Greeks, unlike the Jews or the Christians, invested their gods with human failings. Divine judgment, they believed, was neither flawless nor dispassionate; it was warped by lust, vengeance and self-interest. In the hands of Zeus, the thunderbolt was both an instrument of justice and a weapon of jealousy and revenge.

Those now dispensing judgment from on high are not gods, though they must feel like it. The people striking mortals down with drones are doubtless as capable as anyone else of self-deception, denial and cognitive illusions. More so, perhaps, as the eminent fictions of the Bush years and the growing delusions of the current president suggest.

Barack Obama began last week's state of the union address by claiming that the troops who had fought the Iraq war had "made the United States safer and more respected around the world". Like Bush, like the gods, he has begun to create the world he wants to inhabit.

These power-damaged people have been granted the chance to fulfil one of humankind's abiding fantasies: to vaporise their enemies, as if with a curse or a prayer, effortlessly and from a safe distance. That these powers are already being abused is suggested by the mendacity of those who are deploying them. The CIA, which is running the undeclared and unacknowledged drone war in Pakistan, insists that there have been no recent civilian casualties. So does Obama's chief counter-terrorism adviser, John Brennan. It is a blatant whitewash.

As a report last year by the Bureau of Investigative Journalism showed, of some 2,300 people killed by US drone strikes in Pakistan from 2004 until August 2011, between 392 and 781 appear to have been civilians; 175 were children. In the period about which the CIA and Brennan made their claims, at least 45 civilians have been killed. As soon as an agency claims "we never make mistakes", you know that it has lost its moorings, as Aleksandr Solzhenitsyn suggested in his story of that title. Feeling no obligation to apologise or explain, count bodies or answer for its crimes, it becomes a danger to humanity.

It may be true, as the US air force says, that because a drone can circle and study a target for hours before it strikes, its missiles are less likely to kill civilians than those launched from a piloted plane. (The air force has yet to explain how it reconciles this with its boast that drones "greatly shorten decision time".) But it must also be true that the easier and less risky a deployment is, the more likely it is to happen.

This danger is acknowledged in a remarkably candid assessment published by the UK's Ministry of Defence, which also deploys drones, and has also used them to kill civilians. It maintains that the undeclared air war in Pakistan and Yemen "is totally a function of the existence of an unmanned capability – it is unlikely a similar scale of force would be used if this capability were not available". Citing the German military theorist Carl von Clausewitz, it warns that the brutality of war seldom escalates to its absolute form, partly because of the risk faced by one's own forces. Without risk, there's less restraint. With these unmanned craft, governments can fight a coward's war, a god's war, harming only the unnamed.

The danger is likely to escalate as drone warfare becomes more automated and the lines of accountability less clear. Last week the US navy unveiled a drone that can land on an aircraft carrier without even a remote pilot. The Los Angeles Times warned that "it could usher in an era when death and destruction can be dealt by machines operating semi-independently". The British assessment suggests that within a few years drones assisted by artificial intelligence could make their own decisions about whom to kill and whom to spare. Sorry sir, computer says yes.

"Some would say one man's freedom fighter is another man's terrorist," George HW Bush opined on when he was vice-president. "I reject this notion. The philosophical differences are stark and fundamental." Perhaps they are, but no US administration has convincingly defined them or consistently recognised them. In Latin America, south-east Asia, Africa and the Middle East, successive presidents have thwarted freedom and assisted state terrorism. Drones grant governments new opportunities to snuff out opposition of any kind, terrorist or democrat. The US might already be making use of them.

In October last year, a 16-year-old called Tariq Aziz was travelling through North Waziristan in Pakistan with his 12-year-old cousin, Waheed Khan. Their car was hit by a missile from a US drone. As always, their deaths made them guilty: if we killed them, they must be terrorists. But they weren't. Tariq was about to start work with the human rights group Reprieve, taking pictures of the aftermath of drone strikes. A mistake? Possibly. But it is also possible that he was murdered out of self-interest. If you have such powers, if you are not held to account by Congress, the media or the American people, why not use them?

The danger to democracy, and not just in Pakistan but one day perhaps everywhere, should be evident. Yet, as fatalistic as the ancient Greeks, we drift into this with scarcely a murmur of debate, leaving the gods to decide.

Twitter: @GeorgeMonbiot

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