You know the photo. An American helicopter perches atop a building as would-be evacuees clamber up a ladder to the roof. They’re desperate to flee Saigon, capital of a doomed South Vietnam, before it falls to the communist troops advancing somewhere out of shot below.

A Dutch news agency photographer, Hugh van Es, snapped that picture from his office balcony, on 29 April 1975. The roof belonged to a nearby apartment building where senior CIA staffers were based. It was not the US Embassy, though that’s how it’s been misremembered ever since. Exactly half a century later, van Es’ shot remains engraved in memory as the defining image of how America made its exit.

It also points to something more. In the decades after 1945, the helicopter became the embodiment of the United States’ nimble superpower modernity, descending from on high to bring salvation, or vengeance.

Presidents ducked under the rotating blades to be buzzed from the White House lawn to Camp David, to decide the fate of nations.

Aerospace corporations kept thousands in work in places such as Fort Worth, Texas, the home of Bell Helicopter, which made the UH-1 Iroquois, nicknamed the ‘Huey’. It was one of those Hueys up on that the Saigon roof – at one point, Bell was making 150 every week.

And if war came to America itself? Should the Soviets nuke New York, business leaders planned to pile into choppers and flee to the luxury bunkers awaiting them beneath the Hudson Valley countryside.

When young protesters rebelled against what they saw as their authoritarian, militaristic elders, those same authorities retaliated by sending in the choppers. In August 1968, the Democratic National Convention in Chicago became a fortress. Outside, furious, thwarted left-wing activists demanded a say in the selection of the party’s candidate for president. Mayor Richard Daley sent in baton-wielding cops – and ’copters. In No One Was Killed, his book-length report on the mayhem that followed, the journalist-novelist John Schultz detected the shadow of the hated war in Asia looming over the protesters below:

Overhead, a helicopter yammered up and down the length of Michigan Avenue from the Hilton to 18th Street, playing its searchlight on the crowd rushing north and on the alleys. Perhaps the helicopter was radioing information to the [National] Guard and the cops, but mainly it was there to frighten, to intimidate. Everyone in the crowd knew that in Vietnam a machine gun could be working away behind the searchlight.

Schultz shakes his fist at the cop behind the bulb, imagining him ‘curling his lip at my affront, fingering a trigger and saying, “Oh, what I could do, buddy boy, oh, yes, what I could do”’.

Likewise, nine months later, to disperse huge campus protests at Berkeley, Governor Ronald Reagan dispatched the National Guard. They surrounded the students, while a helicopter swooped in past the university bell tower, pumping out tear gas.

No wonder that, by 1970, such images had come to symbolise implacable, centralised force. In EL Doctorow’s novel The Book of Daniel, the military-industrial complex is described as ‘highly visible’. On a dystopic Californian plain, the protagonist watches a mysterious dark green helicopter track back and forth across the sky all day, ‘its compressions beating the white air till it’s thick’.

Around this time, the US military formalised its long-standing practice of naming its helicopters after Native American tribes (Iroquois, Apache, Chinook) and leaders (Black Hawk). This was reportedly meant to invoke American history while evoking the aircrafts’ stealth and speed. It also underlines the power of the state that was commissioning them. It’s not hard to imagine what the 19th-century federal government would have done with Apache helicopters to actual Apaches.

All the same, these images are more ambiguous than they seem. Helicopters may have left John Schultz feeling powerless as he stared up from the ground, but finally it’s just another person up there, trying to control a tiny, vulnerable vehicle. The helicopter is irreducibly hubristic. It is this that makes it such a potent symbol of the image America presents to itself, and to the rest of us. It hovers, all-powerful, over everything, but sometimes seems a shot away from calamity.

The historian Christian Appy has pointed out that it was helicopters, rather than the far more destructive B-52 bombers, that came to symbolise America’s war in Vietnam. But this is not just because they were incessantly visible over Vietnam itself, and on television: it’s because they embody both sides of the US intervention – omnipotent, and impotent. In Chickenhawk, his bestselling memoir of his year spent flying Hueys early in the war, Robert Mason recalls watching a Viet Cong soldier with a rifle hopelessly trying ‘to take on our entire air-assault battalion, machine guns blazing’. He also describes the intense fear induced by flying low, his ‘chickenshit’ commander hunched low in the seat beside him, and how other Viet Cong fighters took out US pilots – such as Mason’s successor – by shooting vertically through the cockpit from the ground.

This duality was captured in Francis Ford Coppola’s 1979 movie Apocalypse Now, in another spin on these images that are seared into the collective memory. The ascending Wagnerian strings of ‘The Ride of the Valkyries’ are blasted from a helicopter convoy as it swoops in across the sea, effortlessly wiping out scurrying Vietnamese peasants. Yet as soon as one of the choppers lands, a Vietnamese woman runs up and throws in a grenade. And of course that photo from the Saigon roof was only partly an image of American power. It also signified defeat.

More dispiriting images followed. In 1980, with Apocalypse Now still in cinemas, President Carter sent commandos from the Delta Force special missions unit to carry out ‘Operation Eagle Claw’. This was a bid to rescue American diplomats being held hostage in Iran. Three of the eight helicopters malfunctioned. The mission was aborted, in the course of which another crashed into a cargo aircraft, killing eight servicemen.

Three years later, under Ronald Reagan, Delta Force landed in another debacle. ‘Operation Urgent Fury’ was a plan to invade Grenada on the dubious premise that this small Caribbean island, a member of the British Commonwealth, had become a ‘Soviet-Cuban colony’, and a launchpad for terrorism. At one point, Delta Force descended in daylight in Sikorsky UH-60 Black Hawks, struggling through anti-aircraft fire at point-blank range on a mission to liberate political prisoners – only to find the prison empty. Overall, the invasion amounted to something of a political triumph, but, as Reagan’s biographer Max Boot writes, it ‘suffered from many of the same dysfunctions as Operation Eagle Claw’. As if to rub the point in, Robert Mason’s groundbreaking account of the Viet Cong shooting US pilots had touched down in bookstores just weeks before.

By far the most devastating such incident arrived under President Clinton, in October 1993. US forces operating with the United Nations in the war-torn Somalian capital Mogadishu attempted to capture an insurgent leader who had ordered the ambush of a peacekeeping convoy. Once again, Delta Force led the operation in Black Hawks – which had become a focus of Somalis’ anger towards the UN forces. According to the New York Times, even when they weren’t visiting deadly force from the air, their rotors ‘whipped the roofs of whole neighbourhoods’.

The operation, ‘Gothic Serpent’, was a disaster. A soldier fell to the ground from 70 feet up. One Black Hawk crashed; another was shot down. Two Delta Force snipers, deployed by helicopter to secure one of the crash sites, were among the 18 Americans killed. The mutilated body of a US soldier was dragged through the city streets. A helicopter pilot was captured. Images of both men horrified Americans back home: it felt like Vietnam all over again.

After Saigon fell, the philosopher Hannah Arendt wrote that America’s ill-fated intervention ‘was exclusively guided by the needs of a superpower to create for itself an image which would convince the world that it was indeed “the mightiest power on earth”’. Yet that was not shattered by what happened in Iran, Grenada and Somalia. Instead, the image of American power that had once spooked many on the 1960s left began to spook many more in the 1990s, this time on the political right.

When America won the Cold War, it lost its unifying enemy. The ‘New World Order’ that emerged instead felt to some Americans less like victory than defeat, shaped as it was by globalisation, disappearing jobs, the closure of defence manufacturing plants, and then the ascent of Bill Clinton to the presidency: a man they cast as a Vietnam draft-dodger, hell-bent on confiscating patriots’ guns. In reaction against all this, and the violent resolution of sieges at Waco and elsewhere, a large-scale militia movement emerged, some of whose leaders had served in Vietnam.

The beliefs that shaped the movement varied from the extreme right to a much more general discontent, but some of those involved harboured a remarkably detailed vision of imminent tyranny, in which a treacherous federal government, in cahoots with the United Nations, would carve up the republic. This was an early sign of the worldview that has now come to dominate US politics, with its fears of a phantom ‘deep state’, rooted in unease about the federal government’s power. In the 1990s, the image that crystallised this fear was a sinister apparition on the skyline: the unmarked black helicopter.

Throughout this period, there were many reported sightings of these mysterious aircraft, accompanied by ominous theories about what they were up to. In America in Peril, a 1993 talk that circulated widely on video, a militia ideologue called Mark Koernke informed his audience that, at one location, ‘virtual waves’ had been sighted ‘at least four nights in a row… going from horizon to horizon, not in column’. ‘Where’, he demanded, ‘are they coming from?’ In an echo of those scenes in 1968, Koernke revealed that black helicopters had been spotted in Chicago – by individuals staring down from their windows at ‘helicopters flying between the high rises’. This, he said, was part of an operation that cordoned off neighbourhoods and searched house-to-house for guns.

Koernke also set out the role the black helicopters would soon play in the imposition of one-world tyranny on the US. Chinook CH-47s, which could ‘carry up to 64 personnel in one lift’, would drop military forces into a given area of the war-torn US, without regard to ‘road blocks, obstructions, infrastructure damage’. They would also be used to fly detainees from ‘temporary holding sites’ outside the cities ‘to the primary detention site that’s closest, or to a sorting facility, where it will be determined whether or not they are high or low threat’. Veterans and gun-owners, he stressed, need not expect to be released. The dream of American dominance embodied in all those Chinooks and Black Hawks had soured into a very American nightmare.

This was not based on nothing. In 1984, Robert Mathews, the leader of a white supremacist terror group called the Order, ended up in stand-off with law enforcement. It ended when an FBI helicopter fired flares into the house Mathews was holed up in, which reportedly ignited his stash of grenades and ammunition, incinerating him.

FBI helicopters played a role, too, in the besieging of a family of armed right-wing extremists at ‘Ruby Ridge’ in 1992. The following year, yet another siege involving the FBI, this time of a religious cult, developed near Waco, Texas – and there were the Black Hawks. As Jeffrey Toobin writes, a young extremist called Timothy McVeigh remembered watching a woman screaming ‘This is the beast’ at one such chopper. Much as he thought she was ‘a wacko’, McVeigh thought she was right that that ‘the helicopter represented the federal government, which represented evil’.

However unpleasant these incidents were, they did not amount to an attempt to inflict tyranny on the populace. But to McVeigh, the imaginary war, supposedly embodied by those choppers, was becoming dangerously vivid. He talked of doctoring flare launchers to create weapons, with the intention, so he said, of ‘arming the Patriot community with an antihelicopter device’. In 1995, McVeigh blew up the federal building in Oklahoma City, killing 168 innocent people and injuring hundreds more. Some who harboured similar fears of the federal government refused to believe he was guilty, and began to talk of how black helicopters had been seen above the building shortly before the explosion.

The black helicopter motif has persisted in movies such as 1997’s Conspiracy Theory, and in video games. Even one of President Clinton’s own advisers would go on to invoke it. In 2012, Dick Morris published a book called Here Come the Black Helicopters!: UN Global Governance and the Loss of Freedom – though, as Morris and his co-author were at pains to make clear, they did not mean their title to be taken literally. As Arendt had pointed out over Vietnam, helicopters were still just as much about image as reality.

This has continued ever since. The phenomenon has long been particularly visible in the skies above Los Angeles, where the thud of the rotors may signify the presence overhead of the police, or the super-rich – or the media. This took off around the same time as those FBI sieges, as multiple news helicopters raced to find and follow the murder suspect OJ Simpson’s car, as he sped away from the police, turning news into a film shot. Two years earlier, in the Los Angeles riots that followed the intensely controversial acquittal of the police officers filmed beating up a black motorist, another media helicopter inadvertently performed a more useful service. It broadcast live footage of a white truck driver being attacked by rioters – prompting locals, at least one of whom saw the attack on television, to intervene and rescue him.

They were strikingly absent on that occasion, but the LAPD’s buzzing ‘eyes in the sky’ have been a fixture of the city’s life for years. In 2023, Nicholas Shapiro of UCLA suggested to the New Yorker’s Emily Witt that this policing strategy is driven by ‘the idea of being hyper-visible in the sky and their presence being known’. But as Witt notes, there is scant evidence it puts criminals off their stride.

Fifty years on from that chopper on the roof in Saigon, it’s worth looking back at the lesson that picture might have provided – and that might be salient still. Immense power can become hubristic very quickly. If it loses sight of its vulnerabilities, it can all too easily crash to the ground.