The ability to execute its own citizens has been a mark of tyrannical government from Rome in the days of the Caesars to Moscow during the Great Purge in the 1930s

The lack of public response to the British government ordering the assassination by pilotless drones of two British citizens, Reyaad Khan and Rahul Amin, is alarming but scarcely surprising. The two Isis members were killed outside Raqqa in Syria because they were allegedly planning attacks in Britain, though the nature of the threat they posed remains a secret. Their deaths were never going to shock many people in Britain, given IS’s ghastly record for carrying out ritual murders, rapes and massacres.

But the drone attack should cause real alarm because it is an extraordinary extension of the powers of government to be able to execute its own citizens with no explanation, except that the killing was for the public good and against an unnamed but horrendous threat, the nature of which is known only to the government itself. Keep in mind that the ability to execute its own citizens has been a mark of tyrannical government from Rome in the days of the Caesars to Moscow during the Great Purge in the 1930s. Where evidence for an existential threat is lacking, it can be exaggerated or manufactured, as notoriously happened in 2003 over Iraqi WMD.

Avoiding a descriptive word such as “assassination” and the use instead of phrases such as “targeted killings” shows that governments are themselves a little edgy about the rightness of what they are doing. Even so, drone warfare has become highly attractive to political leaders in the US, Britain and the rest of the world. They like it above all because it shows them doing something easily explained and apparently effective against evil-doers of whom their own people are frightened. The use of drones means that there will be no American or British soldiers coming back in coffins, so even if the attacks fail there will be no political price to pay domestically.

In addition, though this justification is a bit discredited these days, the drone strikes can be sold as being of such pin-point accuracy against terrorist leaders that civilian casualties are negligible. The use of drones has all the advantages for politicians of going to war, in terms of rallying public support behind them, but without the costs and uncertainty of real conflict.

The problem is that experience has shown again and again that drone warfare does not work and generally increases the terrorist threat rather than reducing it. The drone strikes become a highly publicised melodrama that substitutes for a real and effective policy. For instance, in September 2011, in Yemen, a US drone killed Anwar al-Awlaki, an American citizen who was one of the leaders of Al-Qaeda in the Arabian Peninsula (AQAP). The Obama administration, which has conducted some 500 drone strikes, presented this killing as a high point in its counter-terrorist campaign. But four years later AQAP is spreading through Yemen, capturing the port city of Mukalla, and stronger than it has ever been. It has done so by taking advantage of the chaos that followed the Saudi military intervention in Yemen in March, which is backed by the US. If Washington is embarrassed by its demonstrable failure in Yemen, it is showing no sign of it, presumably calculating that the rest of the world is paying little attention to the calamitous war there.

Drone strikes and the killing of selected individuals by US special forces have been directed at different times against supposed “king pins” or more junior commanders. The original concept appears to have been pioneered by the Israelis in Gaza, a small besieged enclave where targeted individuals could be easily located and eliminated. Elsewhere, drones were sold by their advocates as a “magic bullet” whereby war could be conducted on the cheap.

Like many simple solutions to complex problems, their shortcomings are easy to describe but difficult to prove – often because the military commanders who owe their promotion to advocating new weapons or strategies have no wish to have their effectiveness accurately tested.

When such measurements do take place, the results are often highly disconcerting and contradict upbeat propaganda claims. A fascinating concrete example of this is given by my brother Andrew Cockburn in his recently published book, Kill Chain: Drones and the Rise of High-Tech Assassins, in a chapter describing the US campaign in Iraq to eliminate “High Value Individuals” held responsible for the IEDs, or Improvised Explosive Devices, that inflicted heavy casualties on US troops. No less than 70,000 of these had been put in place by insurgents by 2007. The counter-measure adopted by the US Army was to target and kill leaders of “the IED networks”, and many were assassinated or otherwise disposed of.

For once there was a rigorous study of what had been achieved, which was carried out by Rex Rivolo, who worked for the Institute for Defense Analysis, the Pentagon’s think tank. Visiting frontline military units with Colonel Jim Hickey, who had led the final, successful, hunt for Saddam Hussein, Rivolo asked about the effect of killing high value individuals (HVIs) on the number of IEDs being used against US troops. Without exception, the soldiers said that the campaign to kill those responsible was counter-effective. One soldier said: “Once you knock them off, a day later you have a new guy who’s smarter, younger, more aggressive and is out for revenge.”

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Rivolo conducted a study on 200 cases where high value targets had been killed or captured between June and October 2007. He looked at the neighbourhood of the local leader who had been eliminated, in order to see if the number of IEDs had gone up or down in the 30 days after his death or arrest. According to the book, it turned out that “hitting HVIs did not reduce attacks and save American lives. It increased them. Each killing had quickly prompted mayhem. Within 3 kilometres of the target’s base of operations, attacks over the following 30 days shot up by 40 per cent.”

The miscalculation by the US Army was political as well as military. It assumed that there were a finite number of insurgents, though by 2007 they must have known they were fighting the six million strong Sunni community in Iraq. Leaders and local commanders could be replaced and they usually were within 24 hours, and, by a Darwinian process of natural selection, the replacements were better able to survive than their predecessors. The main reason why Isis is so militarily expert and successful today is that its commanders are survivors of a dozen years of intense warfare and attempts to kill them.

Of course, drone attacks and assassination teams are nothing like as accurate – or draw on such impeccable intelligence – as they claim, and a significant proportion of those killed in Afghanistan, Iraq, Syria and Yemen have been civilians. Such mistakes have repeatedly occurred and are usually met with official mendacity, evasion and, on occasion, shame-faced admission and payment of meagre compensation. I once reported the bombing of an Afghan village by US planes that had left craters 20ft deep which a US spokesman said might have been caused by grenades thrown by Taliban fighters.

It is into this dubious high-tech world of pretended success and real failure that Britain is entering with its first assassination by drone strike.