‘It is not a function of not trying to take people to Guantánamo,’ the US attorney general, Eric Holder, told a Senate subcommittee on 6 June as he struggled to defend President Obama’s targeted killing programme. His ungainly syntax betrayed his acute embarrassment. He is not the only government spokesman who finds it difficult to answer questions about America’s loosing of drones onto the world.

A central thesis of Mark Mazzetti’s book is that the CIA and the Pentagon have opted to hunt and kill suspected enemies in order to avoid the extra-legal tactics of capture and interrogation adopted under Obama’s predecessor. Mazzetti returns to this charge numerous times, in a characteristically understated way: ‘With few options for detaining terror suspects, and little appetite for extensive ground operations in Somalia, killing sometimes was a far more appealing option than capturing.’ Or: ‘Killing was the preferred course of action in Somalia, and as one person involved in the mission planning put it, “We didn’t capture him because it would have been hard to find a place to put him.”’ In other words, the administration doubled-down on what look suspiciously like extrajudicial executions, faute de mieux, after shuttering Bush’s black sites and deciding not to send anyone else to Guantánamo, where approximately a third of the hundred detainees on hunger strike are receiving a macabre form of Obamacare through tubes in their noses.

Mazzetti adds, as a second unspoken and perhaps unspeakable explanation for Obama’s escalation of drone warfare, that the members of the intelligence establishment were afraid they could be held legally responsible for engaging in torture, a felony under American law. If we follow this account, Obama’s controversial ramping up of drone killings was driven in part by rumblings of rebellion at the CIA, where fear of being hung out to dry by bait-and-switch politicians is legendary. By the time Obama stepped smartly into office, the agency was apparently preoccupied by the possibility that ‘covert officers working at the CIA prisons could be prosecuted for their work.’ This dampened the interrogators’ enthusiasm for extracting information by physically and psychologically abusing their prisoners: ‘each hit the CIA took for its detention-and-interrogation programme pushed CIA leaders further to one side of a morbid calculation that the agency would be far better off killing, rather than jailing, terror suspects.’ According to John Rizzo, a career CIA lawyer, Obama officials ‘never came out and said they would start killing people because they couldn’t interrogate them, but the implication was unmistakable … Once the interrogation was gone, all that was left was the killing.’ Summarising his interviews with Rizzo and other insiders, Mazzetti concludes: ‘Armed drones, and targeted killing in general, offered a new direction for a spy agency that had begun to feel burned by its years in the detention-and-interrogation business.’

The inflammatory implication of this charge is that ‘liberal criticism’ of an unnecessarily harsh and negligently supervised but only sporadically lethal national security policy bears some responsibility for Obama’s swing towards sudden death by drones. Mazzetti himself does not mention it, but the thesis that liberal national security principles produce more cruelty than they prevent has long been a favourite conceit of conservatives. Before he became attorney general in Bush’s second term, Michael Mukasey informed civil libertarians that they, and not those who illegally tortured prisoners of war, were going to have blood on their hands. The offence of the liberals, he claimed bizarrely in the Wall Street Journal, was to advocate judicial oversight of executive decisions about detention: ‘it bears mention that one unintended outcome of a Supreme Court ruling exercising jurisdiction over Guantánamo detainees may be that, in the future, capture of terrorism suspects will be foregone in favour of killing them.’ All that advocates of legal rights were going to achieve was the death of suspected terrorists, not their fair treatment.

But has Obama’s switch from a policy of detain and interrogate to a policy of kill on sight really followed an anti-liberal script written by Bush-era hawks? The speculation has a ring of truth. At the very least, Obama’s armed drone programme is a blood relative of Bush’s original unindicted detention programme. Their kinship is suggested by the shared principle that suspected enemy combatants do not deserve hearings to prove they are innocent of the charges against them. The claim that both policies derive from the same sensibility is also supported by the career trajectory of John Brennan, a veteran of the CIA who recently became the agency’s director. Having served as its deputy executive director under George W. Bush, Brennan returned to government in 2008 as Obama’s chief counterterrorism adviser and, in some accounts, as a kind of father confessor, blessing the president’s lethal strikes as fully compliant with Catholic thinking about morally just wars. Be this as it may, Brennan played a key role in the remarkable transformation of the CIA into ‘a killing machine, an organisation consumed with man hunting’. More concretely, ‘America’s kill list’, during Obama’s first term, was ‘co-ordinated in the basement office of John Brennan’.

There’s a clue here to the origins of Obama’s drone policy. Under Bush, Brennan was an outspoken defender of indefinite detention, rendition to countries with abominable human rights records, and harsh interrogation (though not waterboarding). More to the point, this record was precisely what derailed his hoped-for appointment to head the CIA in 2008. It does not seem far-fetched to assume that, bruised by the backlash against Bush-era counterterrorism measures, Brennan helped to orchestrate the turn to remote-controlled killing machines. This novel method of targeting enemy combatants was much less likely to expose intelligence agents to criminal liability and other career-wreckers. Thus Brennan’s circuitous path to the CIA directorship, especially when viewed alongside his startling statement in June 2011 that drone strikes weren’t killing any civilians, seems to confirm Mazzetti’s recurring suggestion that Obama’s kill-list presidency developed in pursuit of CIA impunity.

That Obama’s inoffensively named ‘overseas contingency operations’ are a lineal descendant of Bush’s Global War on Terror should not be all that surprising. A change in presidents will not occasion a dramatic shift in national security policy if partisan politics, bureaucratic rigidities, vested interests and public opinion have altered only slightly, if at all. As Mazzetti writes, ‘the foundations of the secret war were laid by a conservative Republican president and embraced by a liberal Democratic one who became enamoured of what he had inherited.’

But why exactly did Obama make remote-controlled killing the centrepiece of his counterterrorism policy? This isn’t idle curiosity. Clarity about the administration’s motives is a necessary preliminary to evaluating the justifications it has offered to the public. Mazzetti has made a good start, but a more complete story starts with the rupture between Bush’s and Obama’s approaches to national security. The point is almost too obvious to make, but Obama’s turn to drones followed logically from his vow to disengage from the Bush-era’s land wars of invasion and occupation.

After the 2008 financial crisis, US officials began to doubt the wisdom of devoting massive resources to staggeringly expensive pipe dreams such as sectarian and ethnic reconciliation in Iraq or state-building in Afghanistan. The two wars were still consuming a disproportionate amount of the country’s scarce national security resources, including the attention of top officials. In the meantime, the American electorate had grown ever more indifferent to the wars and sceptical about their contribution to the safety of Americans. To policymakers, it was obvious that the Iraq invasion, having inadvertently created a Shia ally of Iran, was a breathtaking debacle. And in Afghanistan, the soldiers whom the US were teaching to shoot began shooting their teachers, suggesting that America’s ability to impart skills had considerably outrun its ability to inspire loyalty.

Obama parted company with Bush by abandoning hope of turning former state sponsors of terrorism into reliable American allies. Subsequent events have resoundingly confirmed the wisdom of restricting counterterrorism efforts to non-state actors. For instance, the alarming flow of weapons from Gaddafi’s arsenals into Mali and Syria has reminded US officials that disorderly regime change can risk proliferation. The collapse of a dictator in regions where smuggling is a highly developed art is bound to spill dangerous arms into the clandestine arms market, where they can be purchased at bargain-basement prices. Luckily for the nuclear-terrorism-obsessed neocons, Saddam Hussein did not have the weapons they had cited to justify their campaign to topple him.

Indeed, while Obama is struggling to manage the legacy of mutually assured destruction, nuclear deterrence has assumed a radically altered form. Powerful states no longer secure peace by threatening to launch unimaginably destructive weapons at each other. Instead, weak states seek nukes so that they can threaten to lose control of them in the event of foreign support for violent regime change. Bashar Assad was prevented from trying this by the Israeli strike on the Syrian reactor in 2007. But we have to wonder whether his resort to Sarin gas on a small but verifiable scale is intended to make Western powers shudder at the consequences of his regime’s unravelling.

It’s clear enough why Obama decided to end Bush-style wars against alleged state sponsors of terrorism. But why did he authorise an aggressive use of drones? Was it, as his supporters allege, because drone warfare is the most effective way to protect Americans from mass-casualty terrorist attacks? That would be an excellent justification. Unfortunately, it assumes that Obama has a realistic way of calculating the impact of his policy on national security. By writing of Obama’s ‘killing spree’, a term he uses elsewhere to refer to the homicidal rampages of terrorist groups, Mazzetti makes his readers doubt the administration’s sincerity when it issues we-are-making-you-safer defences of weaponised drones. Doubts multiply when we read that the ‘CIA had approval from the White House to carry out missile strikes in Pakistan even when CIA targeters weren’t certain about exactly who it was they were killing’. Before acknowledging that ‘every drone strike is an execution,’ Richard Blee, the former head of the CIA’s bin Laden-hunting unit, told Mazzetti that the CIA lowered the bar for identifying targets because American spies no longer ‘wanted to know who we were killing before anyone pulled the trigger’.

They no longer wanted to know. That is an extraordinary allegation, since deliberate ignorance would increase the chances of criminal liability in the unlikely event that Judgment Day would eventually come. If true, this explodes the pretence that Obama’s targeted killing campaign has been calibrated to increase national security. Curiously, another reason to doubt such assurances can be found in Obama’s admission, in his 23 May speech at the National Defense University, that only one of the four US citizens killed by drones was ‘specifically targeted’. An even more revealing phrase in the same speech was that ‘our operation in Pakistan against Osama bin Laden cannot be the norm.’ However rapidly a Special Forces team executes its mission, such troops risk being captured or killed, igniting a firefight with local forces, or sparking an international crisis. So why did Obama run such risks in this case? Obviously enough, because of the need to make sure, before blasting away, that the proposed target was the right man.

The design and execution of the Abbottabad mission, in other words, contains an implicit confession that drone strikes, even when the operators sincerely want to know who they are targeting, are likely to incinerate look-alikes on the basis of circumstantial evidence. The administration must assume that mistaken-identity executions are tolerable so long as the drone programme makes it much more difficult for whatever is left of al-Qaida (or its affiliates, offshoots and copy-cats) to mount a successful attack on the United States. Acknowledging the ‘hard fact’ that his drone campaign has killed many noncombatants by accident or mistake, Obama confessed in the same speech that ‘For me, and those in my chain of command, these deaths will haunt us as long as we live.’ Contrary to Mazzetti’s report that strikes resulting in collateral damage are ‘cheered in private’, the administration’s official line is that there is no joy in ‘the Predator joystick’. A cheerless conscience is the high personal price US officials have to pay to keep America safe.

But for those defending the strikes, as Mazzetti notes, ‘a single strand of information’, although ‘a shaky basis for a high-risk mission’, provides a sufficient basis for a low-risk mission, one where the US will, at worst, waste an easily replaceable Hellfire missile, but will not endanger the lives of expensively trained commandos. Targeting low-level operatives seems to have been a trend under Obama. A possible if ignoble rationale for this expanding kill list is worth considering. Using a missile to vaporise the Abbottabad compound would have been ill advised because it would have prevented the Navy Seals from acquiring a mother lode of useful intelligence after shooting bin Laden dead. By contrast, obliteration strikes against Yemeni insurgents or ordinary members of the Taliban are unlikely to destroy much intelligence. Yet the absence of exploitable information which makes remote-controlled annihilation unproblematic also makes one wonder how much these strikes contribute to America’s collective self-defence.

Elaborating on these doubts, Mazzetti adds that ‘American missions were often based on shards of intelligence from unreliable sources,’ especially ‘unreliable foreign intelligence services’ who routinely approach their American counterparts bearing cannily compiled and redacted terrorist dossiers. America’s national security operatives, coiled for action and starved of actionable intelligence, are more or less easy to gull, depending on how scrupulously they have invested in sources of intelligence who don’t have an incentive to mislead. Such ruses de guerre are distressingly common in the post-9/11 conflicts and explain, for instance, why Pentagon officials suspected that ‘CIA dispatches … were spoon-fed by Pakistani spies.’ Even inside the CIA, one faction frequently accuses its rivals of being credulous dupes of foreign intelligence services with hidden agendas. But if American national-security officials are so vulnerable to cognitive capture, why do they dismiss concern for mistaken identity as unwarlike delicacy? Could it be that an honest accounting might raise awkward questions about the potentially self-defeating effects of the use of drones?

Rumour has it that CIA drone strikes are more consistently accurate than those conducted by the Pentagon. But the CIA, too, sometimes has a hard time telling who is who. This is true even when its own agents are risking their lives, as was made brutally clear in the infamous December 2009 suicide attack at the forward operating base of Camp Chapman, near Khost in Afghanistan. Seven American agents responsible for picking drone targets inside Pakistan were killed along with a senior Jordanian intelligence officer. The suicide bomber, in a pre-recorded video, claimed the attack was retaliation for the targeted killing campaign being overseen at the base. He had apparently spent months lowering the guard of the US agents by providing intelligence on the whereabouts of low-level operatives who were duly killed by drones. The sloppy screening that allowed the infiltrator to come lethally close to so many top agents was allegedly a gesture of courtesy prompted by his promise to deliver actionable intelligence on the whereabouts of al-Qaida’s number two, Ayman al-Zawahiri.

Unlike other cases of mistaken identity, this one cost American lives. As a result, it could not be hidden from the press. That it casts grave doubts on the ability of the agency’s most skilled drone targeters to distinguish reliably between friend and foe goes without saying. And the report that an American intelligence officer vowed to avenge the attack raises the worry that the desire for revenge may, under cover of secrecy, lead to actions likely to increase, not reduce, terrorist violence. It is worth noting that the bin Laden raid was more retributive than preventive, even if it also yielded useful information about the al-Qaida network. (Placing this backward-looking, non-instrumental logic in the clichéd format of a Hollywood revenge flick was the signal merit of Zero Dark Thirty.) In the dense fog of secret war, fatal mistakes about an individual’s identity, motivation and capacity will inevitably be made. The Camp Chapman debacle therefore brings us back to the initial question: why is Obama still so confident of the righteousness of his secret war by killer drone?

One reason is that anti-American jihadists exploit liberal squeamishness about killing noncombatants for military advantage. From this empirical observation, counterterrorism hawks, who have Obama’s ear, conclude that killing noncombatants is simply the price to be paid for overcoming enemy defences. Another consideration, along the same lines, is that surgical accuracy can be dispensed with if the aim of drone attacks is to discourage enrolment in terrorist training camps and to force our enemies to devote more time to defending themselves than to plotting against us. Immoral it might be, but killing noncombatants will serve these purposes just as effectively as killing combatants.

Of course, the defenders of Obama’s drone programme don’t dwell publicly on such debatable ways of reconciling the justice of drone warfare with the death of innocents that it necessarily entails. Instead, they remind us that conventional warfare involves more collateral damage, more killing of noncombatants, more cases of mistaken identity, more maliciously planted disinformation, and more accumulated misery and mayhem. When US troops invade and occupy a country, the death toll and devastation of property far exceed the literal damage caused by drones dispatched to rub out a high-value target or pick off small groups of real or supposed enemies. This is true even if we take avoidable and unavoidable mistakes into account.

In other words, a wish to improve America’s tarnished image abroad must have been another factor in Obama’s decision. A shift from land armies with heavy weapons and embedded journalists to lightweight deniable drones promised to staunch some toxic anti-American PR, as well as to limit the haemorrhaging of US treasure. Hellfire missiles are mostly fired into remote and inaccessible regions. And the cost to America’s reputation remains as negligible as the sticker price so long as the missiles sow death where few journalists can poke around in the ashes. But a budgetary squeeze and aversion to bad publicity merely supplement other non-strategic motivations for drone warfare, including the absence of appropriate detention facilities, stressed by Mazzetti, as well as Obama’s need to parry Republican charges that he is naive about lethal threats and to authorise something (short of another land war) to satisfy the national security bureaucracies.

Such miscellaneous drivers of Obama’s drone policy are worth keeping in mind. But we need to dig deeper still. We cannot articulate clearly what is so disturbing about drone warfare without first attempting to make the strongest possible case for Obama’s approach. That conventional wars are more destructive than drone wars is a reasonable place to start, although we also need to remember that Obama initially expanded the use of armed drones not to replace but to supplement counter-insurgency. The ability of anti-American fighters to retreat into unassailable mountain redoubts in the tribal areas of northwestern Pakistan has been perhaps the greatest thorn in the side of the coalition’s abortive efforts to stabilise Afghanistan. Drones provide a devastating answer to this enduring problem. They neutralise the principal tactic by which relatively weak insurgents win wars against militarily superior foreign forces. Insurgents can win by raising the price of their enemy’s continued involvement in the conflict, mostly by inflicting fatalities that prove unacceptable to the domestic constituencies of the occupiers. It is not hard to imagine Obama becoming ‘enamoured’ of drones for this reason alone: they have allowed him to wage war in remote badlands while depriving America’s enemies of any straightforward way to raise the price of his staying in the fight.

But Obama can make an even subtler case for drones. Well-meaning but imperfectly informed critics sometimes claim that the absence of risk to US forces explains the recklessness with which American drone operators kill combatants and noncombatants alike. Mazzetti quotes, in this context, Richard Clarke’s comment on the routinisation of asymmetry in drone warfare: ‘if the Predator gets shot down, the pilot goes home and fucks his wife. It’s OK. There’s no POW issue here.’ That noncombatants are regularly killed by pilots of unmanned aircraft sticking to their routines is widely acknowledged. But does it make sense to argue that such documented overkill results from the absence of risk to the pilots’ own lives and limbs? Obama and his supporters, rightly in my view, dismiss this line of attack as theoretically confused and empirically unproven. For one thing, the stress, panic and fear experienced on combat missions can easily increase rather than decrease the number of mistaken hair-trigger strikes on noncombatants. Reckless endangering of civilians results more often from heat-of-battle fear than from above-the-battle serenity. The drone operator is freed from the pressures of kill or be killed that can easily distort interpretations of what one sees, or thinks one sees, on the battlefield. The faux cockpits from which drones are remotely piloted are unlikely to be commandeered by berserkers.

An even more powerful, if still flawed, argument in favour of Obama’s campaign is the way heavy losses in any war can subconsciously put pressure on civilian politicians to inflate irrationally the aims of the conflict in order to align them with the sacrifices being made. War aims are not fixed ex ante but are constantly evolving for the simple reason that war is essentially opportunistic. Initial objectives that prove unrealistic are discarded as new opportunities emerge. Far from inducing greater caution in the use of force, heavy losses of one’s own troops may exacerbate a tendency to demonise the enemy and to hype the goals of the struggle.

Formulated more abstractly, the way we fight has a marked impact on when and why we fight. This is true despite what experts in the laws of war tell us about a theoretically watertight separation between jus in bello and jus ad bellum. Fighting in a way that limits the risk to one’s own troops makes it possible to fight limited-aims wars that don’t spiral into all-out wars for national survival. This, I think, is Obama’s best case for drone warfare. Land wars are ‘dumb’ because they almost inevitably involve mission creep as well as postwar responsibilities that US forces are poorly equipped to assume. Drone warfare is smart because, while helping dismantle terrorist organisations and disrupt terrorist plots, it involves less commitment on the American side, and is therefore much less likely to escalate out of control.

It is a good case, but not good enough. And it will certainly do nothing to satisfy drone warfare’s most far-seeing critics. To understand why not, we need to re-examine the sources of disquiet with drone warfare that such defences, however reasonable they sound, utterly fail to address. Doubts about Obama’s programme of targeted killing are not rooted in some dim notion that drone technology is especially creepy. Nor do its critics allege that killing the enemy without risking one’s own life is somehow cowardly. They do not deny the obvious fact that Obama has radically reduced the US military’s footprint in foreign countries. And they acknowledge that armed drones have been essential for dismantling the al-Qaida network in northwest Pakistan. As Mazzetti’s on the record interviews reveal, Obama’s harshest critics even agree that ‘the drone programme is the most effective covert-action programme in CIA history’ but nevertheless argue vehemently against the way drones are being deployed.

So what are the sources of their foreboding? The first is the disconcerting list of non-strategic reasons why Obama might have found drone warfare appealing. Such a multitude of factors does not refute the proposition that he expanded the use of armed drones solely to make Americans safer. But examining them at leisure does increase one’s doubts. Second, even if we put such doubts aside, we cannot help noticing that the administration’s justifications of ‘the quick fix of killing mid-level terrorists’ are all short term. Likely long-term consequences are swept under the rug. When we try to evaluate Obama’s decision to ‘embrace targeted-killing operations as the future of American warfare’, we need to make out what kind of future he has in mind.

This is the crux of the problem. We stand at the beginning of the Drone Age and the genie is not going to climb back into the bottle. The chances that this way of war will, over time, reduce the amount of random violence in the world are essentially nil. Obama’s drone policy has set an ominous precedent, and not only for future residents of the White House. It promises, over the long term, to engender more violence than it prevents because it excites no public backlash. That, for the permanent national security apparatus that has deftly moulded the worldview of a novice president, is its irresistible allure. It doesn’t provoke significant protest even on the part of people who condemn hit-jobs done with sticky bombs, radioactive isotopes or a bullet between the eyes – in the style of Mossad or Putin’s FSB. That America appears to be laidback about drones has made it possible for the CIA to resume the assassination programme it was compelled to shut down in the 1970s without, this time, awakening any politically significant outrage. It has also allowed the Pentagon to wage a war against which antiwar forces are apparently unable to rally even modest public support.

The absence of political opposition is what Mazzetti has in mind when he writes, paraphrasing Richard Blee, that ‘the pistons of the killing machine operate entirely without friction.’ This suggests that Obama adopted a take-no-prisoners policy because escalating a programme that had already begun to expand under Bush was the path of least resistance. Under cover of darkness, illicit and even dishonourable motives often steal into the policymaking process. In warfare, the tendency of existing means to define the ends in view leads to a situation where, instead of our deploying weapons to achieve our clearly thought-out objectives, the newest weapons system to hand may distort our understanding of what objectives are worth pursuing. Could that be happening here? It is one thing if Obama is killing only those who have the intention and capacity to massacre Americans. It is quite another if he is dealing out death in pursuit of ordinary foreign policy goals because it has become so mercifully easy to do.

In ‘the years before the 9/11 attacks’, the principal reason CIA officials urged the development of the armed Predator was ‘to hunt and kill bin Laden in Afghanistan’. This historical detail gives one pause. A major reason atomic bombs were dropped on Japan is that Hitler, their original target, was already dead. So might the US be striking low-level operatives, for no strategic gain, because bin Laden, for whom the armed drone was developed, is no longer with us? This is what sceptics have in mind when they complain that the drone programme has taken on a life of its own or that tactics have swallowed strategy. They fear that, relieved by secrecy of having to provide plausible reasons for its actions, the US is deploying drones mostly because it invested so much effort in developing them. Enchanted by an amazing new weapons system, the US government, so they fear, may be killing simply out of inertia, not because its targets pose a real threat to the lives of its citizens.

Unsupervised privatisation of national security functions, alongside bureaucratic fragmentation and duplication in the executive branch, make it relatively easy for national security operatives to hide the ball from Congress and the press. But those who complain about the lack of any serious oversight of executive action in this field are concerned less with practical difficulties than with the impossibility in principle of making preventive warfare politically accountable. It seems likely that the ‘necessity’ invoked to justify killing terrorist suspects outside war zones is indistinguishable in practice from mere desirability as determined by anonymous national security operatives. Common sense suggests that at least some of the thousands of alleged militants killed by drones have been killed unjustly: that is, have not been killed in America’s collective self-defence, however capaciously understood. The numbers alone suggest that the US sometimes targets nobodies, that the gravity and urgency of the threat are not being carefully considered, and that the foiling of imminent attacks cannot be the sole or perhaps even the main justification for killing by drone. But these reasonable suspicions have no legal purchase because no impartial body can, with confidence, evaluate executive branch guesses about which militants scurrying around inaccessible parts of the world pose a grave and enduring threat to Americans.

Critics also fear the programme’s hidden costs, especially its hidden opportunity costs. Targeted killing seems to be siphoning scarce resources, including the personal attention of the president, away from threats that are extremely serious but have to be managed gradually over time and towards arguably trivial threats that can, once in the crosshairs, be bug-splatted away. Paradoxically, the allegedly high success rate of individual drone strikes may have strategically negative consequences. The notorious lack of any metric to measure the reduction in the long-term threat to national security may make personality or pattern-of-life strikes appear more strategically valuable than they are simply because they can be counted.

Obama rightly boasts that he has extracted the country from land wars. But he is simultaneously sleepwalking it into new conflict zones around the world. He would presumably not be doing this had drone warfare not been an available option. In his 23 May speech, speaking about the war America launched in the wake of 9/11, he said: ‘this war, like all wars, must end. That’s what history advises. That’s what our democracy demands.’ What he apparently meant to say was that he has found a way for this war to continue without penetrating the consciousness of US citizens. That is apparently what American democracy demands. The instrument that has allowed him to narrow the fight guarantees that the fight will go on. Obama came into office promising to restrict and reconfigure the country’s counterterrorism efforts, to bring them back within the rule of law. Instead, he too is fighting fire with fire. He continues to play according to bin Laden’s archaic playbook, perpetuating an endless post-9/11 revenge cycle, tit for tat. The Khost tragedy, where revenge against drone strikes justified further revenge strikes by drone, is a case in point.

On the basis of undisclosed evidence, evaluated in unspecified procedures by rotating personnel with heterogeneous backgrounds, the US is continuing to kill those it classifies as suspected terrorists in Somalia, Yemen and Pakistan. It has certainly been eliminating militants who had nothing to do with 9/11, including local insurgents fighting local battles who, while posing no realistic threat to America, had allied themselves opportunistically with international anti-American jihadists. By following the latter wherever they go, the US is allowing ragtag militants to impose ever new fronts in its secret aerial war. Mistakes are made and can’t be hidden, at least not from local populations. Nor can the resentment of surrounding communities be easily assuaged. This is because, even when it finds its target, the US is killing not those who are demonstrably guilty of widely acknowledged crimes but rather those who, it is predicted, will commit crimes in the future. Of course, the civilian populations in the countries where these strikes take place will never accept the hunches of CIA or Pentagon futurologists. And so they will never accept American claims about the justice of Obama’s slimmed-down war on terror, but instead claim the right of self-defence, and this would be true even if drone operators could become as error-free as Brennan once claimed they already are. But of course collateral damage and mistaken-identity strikes will continue. They are inevitable accompaniments of all warfare. And they, too, along with intentional killings that are never publicly justified, will communicate resoundingly to the world that the arbitrary and unpredictable killing of innocent Muslims falls within America’s commodious concept of a just war.

The rage such strikes incite will be all the greater if onlookers believe, as seems likely, that the killing they observe makes relatively little contribution to the safety of Americans. Indeed, this is already happening, which is the reason that the drone, whatever its moral superiority to land armies and heavy weaponry, has replaced Guantánamo as the incendiary symbol of America’s indecent callousness towards the world’s Muslims. As Bush was the Guantánamo president, so Obama is the drone president. This switch, whatever Obama hoped, represents a worsening not an improvement of America’s image in the world.

But it follows a compelling logic. Under Bush, the US justified holding enemy combatants by classifying their captivity as law-of-war detention. But law-of-war detention presupposes that the war in question will end and that the detainees will then be released. Once Obama concluded that this war will never end, he presumably drew the sensible inference that traditional law-of-war detention is wholly inapplicable to the unconventional conflict in which the US is now engaged. That is when he made his fateful choice: the moment when he turned to the only form of incapacitation appropriate to a war without end. In so doing, he has bequeathed to us not a war that will be easier to contain, but one that is borderless and self-sustaining and that shows not a single discernible sign of burning itself out.