In​ 1973, Harold Hering, a decorated Vietnam War rescue pilot, was studying at Vandenberg Air Force Base to become a missile launch officer, a member of an elite group charged with executing the order to launch a nuclear strike. The responsibility was immense, but Hering was persuaded that, at the crew level, there were enough checks and balances to guard against rash behaviour on the part of any individual. Still, he wondered whether anyone was checking the president, the commander in chief of the US armed forces, who appeared to have the sole and personal power to order the strike. What, if anything, could prevent the president – at the time, it was Nixon – from making a catastrophic decision? (‘That raised the hair on the back of my neck, a little bit,’ Hering remembered in an interview with Radiolab earlier this year.) His instructor requested that he put his question in writing. ‘There’s presently a degree of doubt in my mind as to whether I might one day be called upon to launch nuclear weapons as a result of an invalid or unlawful order,’ Hering wrote to his superiors. ‘How can I be sure I’m participating in a just act?’

It wasn’t an unreasonable question. Nixon had flirted with using nuclear weapons in conversations with Henry Kissinger during the North Vietnamese offensive of spring 1972. When Kissinger told him it ‘would just be too much’, Nixon was outraged: ‘I just want you to think big, Henry, for Christsakes.’ Kissinger soon learned to think big. At the Paris peace talks in December, he reportedly issued no less than a dozen nuclear threats to North Vietnamese negotiators.

Hering never got a reply to his letter. Instead, six days before he was supposed to graduate, he was removed from training, stripped of his flight status and top secret security clearance, and ultimately forced to retire from the air force. He became a truck driver and counselled addicts and homeless people for the Salvation Army. He had no regrets: ‘I felt I had asked a very reasonable question that deserved an answer, and it was not for me alone, it was for all of us.’

Hering was questioning one of the foundations – the foundation – of US nuclear policy since Truman authorised the attacks on Hiroshima and Nagasaki: that the president has the exclusive power and legal authority to order a nuclear strike. He or she is encouraged to consult with the secretary of defence, as well as regional ‘combatant commanders’, but the final decision to launch a strike is, at least in theory, the president’s alone.

‘Bomb power’, as Garry Wills called it in a 2010 book, is inseparable from the office of the presidency. Investing the president with the exclusive power to launch a nuclear weapon was originally intended to protect the United States from military officers eager to try their toys out on the battlefield. The idea was that a civilian president would be less inclined to use such weapons without considering their full effects; and besides, the electoral system ensured that the president would be a responsible person, temperamentally reluctant to place the entire planet at risk. The Trump presidency has severely tested both these beliefs, reigniting a lingering fear of nuclear war, if not nuclear annihilation, a fear that many of us had forgotten, or at least learned to repress, after the Cold War. Once again, the newspapers are full of not-so-hallucinatory scenarios of the steps to apocalypse, while the sabre-rattlers-in-chief – Donald Trump and Kim Jong-un – trade insults like schoolchildren locked in a brawl.

Of course the threat of nuclear war never vanished. All that went away was the bipolar conflict with the Soviet Union, the theatre in which we feared the war would erupt. As E.P. Thompson wrote, ‘it has never been true that nuclear war is “unthinkable”. It has been thought and the thought has been put into effect.’ The Western model of capitalism may have won – or survived – the Cold War, but so did the bomb. In fact, the bomb proliferated, and new nuclear powers emerged, driven by conflicts scarcely related to superpower confrontation. Thanks to the collapse of communism, we are no longer sure that ‘the golden age is within us,’ as Lévi-Strauss said, but there’s no doubt that the apocalypse is. And the fear of nuclear war is heightened by the raw, primordial tenor of our politics, above all in the United States. What Pankaj Mishra has called an ‘age of anger’ is also an age of disinhibition, at least on the political right, and it is embodied by the US president, who has set in train a loosening of moral restraints in every sphere.

The United States is now governed by someone who seems to revel in bomb power, and who seems indifferent to, if not unaware of, its consequences; a man who wonders why the US doesn’t use its nuclear weapons since, after all, it has so many of them; a man who speaks unhesitatingly of eliminating other nations. The ‘depraved state’ of North Korea is, of course, his favourite potential target. Incinerating North Korea in a pre-emptive strike would be an act of self-defence, as Trump sees it: in his speech to the UN General Assembly, he said that the US ‘will have no choice but to totally destroy North Korea’ if ‘Rocket Man’ develops a weapon that can reach Denver. (Like genocide, nuclear war is invariably depicted as self-defence by those who favour it.) Iran, with whom the loathed Obama signed a nuclear agreement (described by Trump as ‘one of the worst and most one-sided transactions the United States has ever entered into’), is preferred target number two. He has ‘decertified’ the Iran agreement, leaving it to Congress to decide whether the US will continue to honour it, and raising the distinct possibility, should the US abandon it, that Iran’s leaders will pursue nuclear weapons, if only to protect themselves from the sort of attack that ousted Gaddafi, after he ended Libya’s nuclear weapons programme in 2004.

Occasionally, there are signs of normality, emanating mostly from the mild-mannered secretary of state, Rex Tillerson, who has insisted that, in the case of North Korea, diplomacy ‘will continue until the first bomb drops’. But Tillerson isn’t in the nuclear chain of command, and Trump wasn’t pleased when Tillerson called him a ‘moron’ for requesting a tenfold increase in the US nuclear arsenal. It’s one of the peculiarities of the American political system that you can call the president a moron – or, as Thomas Friedman recently put it on the front page of the New York Times, ‘flat-out dumb’ – but you can’t call into question the sanctity or power of his office. Whatever your complaints, the president has ultimate military authority, and there are plenty of indications that this one is bent on confrontation. Diplomacy is for losers. For the first time since 1991, when the Soviet Union collapsed, the US air force is preparing to put B-52 bombers on 24-hour alert. It isn’t only Democrats who are frightened. In a remarkable interview on 8 October, Bob Corker, a Republican senator from Tennessee, said Trump was leading the US ‘on the path to World War Three’. Corker is one of a handful of Republicans, along with John McCain and Jeff Flake, who now seem more afraid of what Trump might do to the world than of what he might do to them.

What sort of war does Trump risk detonating? The most frightening scenario is war between ‘Rocket Man’ and ‘the Dotard’ (as Kim Jong-un calls Trump). An American strike on North Korea is all but guaranteed to trigger a North Korean retaliatory attack on South Korea and Japan, and possibly the West Coast of the United States. Aside from the enormous death toll, the strike would imperil the international system of alliances and promote further proliferation. But even if Trump shows that he is capable of restraint towards North Korea and Iran, his contempt for diplomacy could undermine faith in international agreements, feed proliferation and increase the chances of nuclear clashes.

In late October, Senator Ed Markey of Massachusetts and Congressman John Conyers of Michigan, a veteran of the Korean War, introduced a bill to prevent Trump from launching a strike against North Korea without a congressional declaration of war. But the ‘No Unconstitutional Strike against North Korea’ bill has only 61 backers in the House, and it’s hard to imagine the bill passing when Congress has in practice given up the power to declare war: no such declaration has been made since 1942. (Markey also co-authored, with Ted Lieu, a Democratic congressman from Los Angeles, a more ambitious and no less quixotic bill to prohibit first use of any nuclear weapon without a congressional declaration.) As Arthur Schlesinger pointed out forty years ago in The Imperial Presidency, Congress ‘almost came to love its impotence’ during the Cold War: ‘The image of the president acting by himself in foreign affairs, imposing his own sense of reality and necessity on a waiting government and people, became the new orthodoxy.’ Schlesinger quotes Carl Vinson – a Democrat from Georgia who served in Congress from 1914 to 1965, the years in which Congress surrendered its war-making power to the president – comparing Congress’s role in war to ‘that of a sometimes querulous but essentially kindly uncle who complains while furiously puffing on his pipe, but who finally, as everyone expects, gives in and hands over the allowance, grants the permission, or raises his hand in blessing, and then returns to his rocking chair for another year of somnolence broken only by an occasional anxious glance down the avenue and a muttered doubt as to whether he had done the right thing’. Today it’s inconceivable that Congress would be consulted in the event of a nuclear attack, and, in any case, most of those in Congress secretly prefer this arrangement. ‘What Congress wants isn’t power so much as deniability,’ Stephen Holmes has suggested. It is less interested in claiming a president’s successes than in disowning his failures.

‘He is sovereign​ who decides,’ in the words of the Nazi jurist Carl Schmitt, and the American president’s bomb power is one of the purest illustrations, at least on paper, of Schmitt’s argument. The chain of command runs from the commander in chief to the secretary of defence (whose counsel is recommended, but not mandatory) to the regional ‘combatant commanders’ (CCDRs), who would execute the order to launch an attack. The CCDRs used to be known as ‘commanders in chief’ (CINCs, pronounced ‘sinks’), but in 2002 they were demoted by Donald Rumsfeld, on the grounds that there can be only one commander in chief, the president. CCDRs are trained to execute orders, not to question them – Hering’s unpardonable offence. Only a brazenly independent-minded CCDR would dare to challenge a presidential order. The nuclear arsenal is designed to respond to such an order within minutes: there’s no time for questions. Senator Dianne Feinstein of California recently asked a former head of US Strategic Command if he would carry out an execute order that he knew would have disastrous consequences: ‘He looked me straight in the eye and said: “Yes.”’ The idea that the wise men of the Joint Chiefs of Staff would dissuade Trump from a reckless attack is little more than a fable: they aren’t even part of the chain of command.

And what about the four-star generals who surround Trump: James Mattis, who as secretary of defence is second in the chain of command, or John Kelly, the chief of staff, who isn’t in the chain of command but would probably be consulted on the decision? ‘These are people who have grown up saying, “Yes, sir,”’ Andrew Bacevich, a retired career officer in the US army, replied when I put the question to him. (In his recent speech following the death of four American soldiers in Niger, Kelly essentially said that the best Americans are lying in the ground of Arlington Cemetery.) Generals tend to be more cautious about the use of force than civilian leaders, it’s often argued, because they’ve known war – but the counterargument, as Bacevich says, is that ‘we now have generals who know nothing but war. And the notion that force is a last resort, which was common a half-century ago, is gone. There’s a different mindset within the national security apparatus from the one that existed during the Cold War, and that changed mindset could reduce inhibitions when it comes to using force on a much larger scale.’

What’s really terrifying about Trump’s control of the bomb is that it’s no aberration: in fact, it’s utterly normal. Democratic politicians – presidents, and would-be presidents – have spoken with no less gusto of their willingness to ‘keep all options on the table’. When Obama said that he wouldn’t consider using nuclear weapons against Pakistan at a presidential debate in 2008, Hillary Clinton scolded him: ‘I don’t believe any president should make blanket statements with regard to use or non-use.’ The right to annihilate one’s enemies (or frenemies, as in the case of Pakistan) is a right no American leader can afford to relinquish, for fear that he or she would be accused of being a pushover, an appeaser – a pussy. (A president can only grab a pussy: he can’t be one.) When Obama tried to discuss a no-first-use declaration, his cabinet quickly dissuaded him. Although he achieved the nuclear agreement with Iran, averting a potential war, and expressed symbolic atonement on his visit to Hiroshima, he also oversaw a programme of nuclear modernisation, with a commitment to a trillion dollars in extra spending over thirty years, increasing America’s ability to crush its opponents in a first strike. Trump has happily inherited that programme, without, of course, crediting his predecessor.

America’s system of nuclear decision-making was set up by Truman, who was determined to keep the bomb out of the hands of the military. Truman had authorised the use of atomic weapons, but, according to the historian Alex Wellerstein, who maintains the blog Nuclear Secrecy, he had been persuaded, or somehow persuaded himself, that Hiroshima was a military base, and only soldiers would be killed. Although he never expressed contrition, the death of hundreds of thousands of civilians left him wary of nuclear weapons, and fearful that the military would initiate further strikes (more strikes against Japan were planned immediately after Nagasaki, but Truman called them off). To assert full presidential control over the bomb, Truman made sure that the nuclear parts of the atomic bombs, known as ‘pits’, were kept by the civilian Atomic Energy Commission, a precursor of the Energy Department. They were guarded by men with guns, who had orders to shoot anyone who tried to remove them; the military, which held the non-nuclear parts, required the president’s permission to reassemble them.

The balance of power between the president and the military would undergo a number of shifts after Truman. Eisenhower, a general, had fewer qualms about the bomb, or about ceding authority to the military. Under his watch, 90 per cent of America’s nuclear arsenal was transferred to the military, a decision driven in part by changes in technology – nuclear weapons could no longer be separated from their delivery devices. ‘If you had physical access to the weapons, you could use them,’ Wellerstein says. Kennedy, alarmed by how easy Eisenhower had made it to use nuclear weapons, introduced new controls, including an intricate system of locks and codes designed to create a more coherent system of command with the president at its apex, but he didn’t shy away from brinksmanship during the Cuban missile crisis.

The official rationale of the US nuclear programme, throughout the Cold War, was to deter a Soviet attack, but according to Daniel Ellsberg in The Doomsday Machine, his forthcoming memoir of his time at the Defence Department and the Rand Corporation in the 1950s and 1960s, the actual purpose was to ensure that there could be no Soviet retaliation. In other words, US nuclear policy was designed for first use, rather than for a response to a Soviet strike. And though the bomb wasn’t deployed again in combat after Nagasaki, Eisenhower, Kennedy and Nixon all used it to threaten and bully their enemies. In 1976, the New York Times reported that in the summer of 1974, Nixon, exasperated by the Watergate investigation and drinking heavily, told two congressmen that he had more exalted responsibilities than answering questions about the break-in at the Democratic National Committee headquarters: ‘At any moment I could go into the next room, push a button and twenty minutes later 60 million people would be dead.’ He may have spoken out of turn, but he wasn’t wrong. Presidential bomb power and first use were, and remain, the real pillars of the US nuclear posture.

One of the first people to register the dangers of this system was the constitutional scholar Edward Samuel Corwin. In a series of lectures delivered at the University of Michigan in 1946 (later published as Total War and the Constitution), Corwin argued that the American state had been irreversibly altered by the dramatic expansion of executive power during the Second World War, particularly after the bombing of Hiroshima and Nagasaki. Corwin had been an adviser to Roosevelt, and supported his attempt to ‘pack’ the Supreme Court with judges sympathetic to the New Deal, but he was troubled by the slide into presidential dictatorship. Bomb power, he believed, had its roots in what he called ‘the war before the war’: the American Civil War, when Lincoln, an eloquent critic of executive war-making power during the US-Mexico War, became its most aggressive champion, suspending the writ of habeas corpus. With the Lend-Lease Act of 1941 (which authorised the provision of US military aid to its allies a year before America’s official entry into the Second World War), Roosevelt presided over an even bolder seizure of war-making power by the executive. In 1942 he promised that when the war was over, ‘powers under which I act automatically revert to the people – to whom they belong,’ but, as Corwin observed, the statement merely demonstrated how much power had already been taken away from Congress: ‘The implication seems to be that the president owed the transcendent powers he was claiming to some peculiar relationship between himself and the people – a doctrine with a strong family resemblance to the leadership principle against which the war was supposedly being fought.’ From then on, Congress’s authority over the conduct of war would become, as Corwin predicted, ‘little more than the power to announce formally to the world that the United States is at war’.

Trump’s​ exaltation of executive power may strike his critics as preposterous, as well as deadly, but it seems entirely appropriate to his base, the 35 to 40 per cent of the electorate who remain unmoved by Robert Mueller’s recent arrests. It also reflects an indisputable reality: the progressive erosion of checks and balances on presidential war-making power. The president is now understood as the sovereign who decides, not just for the United States, but, given the enormous size of the US arsenal, for the world. The image of the president-decider is best illustrated by the so-called nuclear ‘football’, a 20 kg black leather satchel that contains a computer with the nuclear codes by which execute orders are transmitted, the first of these being the ‘biscuit’ or ‘golden code’ that confirms the president’s identity. It’s likely that not much more would precede this fateful step than a short conference call with James Mattis and John Hyten, commander of the strategic forces near Omaha, Nebraska. Once the Pentagon receives the correct codes, it sends the president’s launch order – the length of a tweet – to the forces designated by the order. Ground crews are prepared to execute the president’s decision within five minutes of the launch order, or 15 minutes for nuclear submarines. Like his predecessors, Trump is accompanied on all excursions by the aide who carries the football, at the moment a young, genial-looking African-American man named Rick. We know this because he was photographed last February at Mar-a-Lago by the retired fund manager Richard DeAgazio, a Trump supporter who cheerfully posted the photograph of himself and Rick on Facebook, along with Rick’s job description. The North Koreans had just carried out a ballistic missile test, interrupting Trump’s dinner with the Japanese prime minister. ‘Rick is the Man,’ DeAgazio wrote on Facebook after the meal.

The football post reflected the culture of unbridled exhibitionism in Trumpworld, the simultaneous embrace of presidential power and indifference to presidential decorum, but there’s no taboo against the image of the football in American politics. On the contrary: at the moment of a president’s swearing in, the football carrier is supposed to turn his or her gaze away from the departing president towards the new one, in a televised ceremony indicating that the commander in chief’s godlike powers have been transferred. That’s the theory, at least.

In reality, the president’s power to launch a nuclear strike may be less exclusive than we imagine. It’s well known that Eisenhower granted high-ranking commanders in the field authority to carry out nuclear strikes in emergency situations, a practice known as ‘pre-delegation’. The purpose of pre-delegation was to send a message to the Soviets that they couldn’t cripple America’s retaliatory capacity by decapitating the presidential command in Washington. (The Soviets had reciprocal pre-delegation, for deterrence or, in the worst-case scenario, mutually assured destruction.) The US has officially denied the existence of pre-delegation, but Ellsberg claims the hand on the button has never been exclusively that of the president or the highest military officials. If he’s right, the president’s monopoly on bomb power would turn out to be a myth, cultivated to conceal the workings of a deep nuclear state embedded in the US military command.

Wellerstein doubts that pre-delegation today is more extensive than it was in the 1950s. But Ellsberg, who draws abundantly on his experience as a consultant at the highest levels of the national security system, raises the possibility that it is, and his account is far from reassuring. Pre-delegation would be even scarier than exclusive presidential bomb power, because it adds a further element of unpredictability – more hands, without more checks – to an already volatile situation. It’s important to remember that the threat invoked to justify a nuclear strike is seldom clear. Just about the only thing ‘we can state, unequivocally’, the authors of a 1956 Rand report cited by Ellsberg conceded, is that ‘the signals indicating a Soviet attack will be equivocal … The ambiguity of strategic warning complicates the problem of decision.’ No doubt it does; it also increases the possibility of false alarms, and hasty judgments, particularly if the president is as impulsive as Trump; and all the more so if he has reason to distract the public’s attention from indictments against his allies. One can all too easily imagine a situation in which Trump’s bellicose threats to North Korea or Iran elicit bellicose counter-threats, leading to clashes in the Korean peninsula or the Persian Gulf. Ellsberg suggests that in the event of such a clash, the execute orders might not be made solely by the president, but by combatant commanders or even their subordinates. According to Lawrence Wilkerson, Colin Powell’s former chief of staff, the current nuclear situation is ‘as dangerous as it’s been since 1945’.

It would be comforting to think that Trump is the problem when it comes to the threat of a nuclear war, and that once he’s removed we can breathe freely again, as we imagined we did under Obama. But what we mistook for safety was more like sleepwalking. As George Kennan observed during Reagan’s nuclear build-up, ‘we have gone on piling weapon upon weapon, missile upon missile, helplessly, almost involuntarily, like the victims of some kind of hypnosis, like men in a dream, like lemmings headed for the sea.’ To be sure, Trump raises the risk of nuclear confrontation in a way that most of his predecessors took pains to avoid. But the problems run much deeper than Trump, a grotesque symptom of a national malaise. One of these problems is the dysfunctional state of US democracy, which was supposed to provide a guarantee against politicians who might misuse nuclear weapons. Another is the persistence of a system designed for a conflict that ended in 1991, a system defined by the imperial presidency and a commitment to first strike capacity. As Corwin warned, America’s wartime transformation, and the emergence of the national security state, has cast a long, seemingly infinite shadow over peacetime. Perhaps the question we should be asking is not whether Trump can be stopped, but whether the system as a whole can be overhauled. ‘We have elevated the president to the position of a demigod, and then when he turns out to be Donald Trump, we’re shocked,’ Bacevich said to me. ‘But since Roosevelt we have vastly enhanced the power and prerogatives exercised by the president, and his ability to execute the nuclear war plan is just part of the package. Why have we entrusted this one imperfect individual with the power to blow up the planet?’ It’s the question that cost Harold Hering his job, and it’s about time more of us started asking it.