Article originally appeared in The Independent (UK)

Do you know the story of the grizzly bear that nearly destroyed the world? It sounds like a demented fairytale — but it is true. On the night of 25 October 1962, when the Cold War was at its hottest and Kennedy and Krushchev’s fingers were hovering over the nuclear button, a tall, dark figure tried to climb over the fence into a US military installation near Duluth, Minnesota. A panicked sentry fired at the figure but it kept coming — so he sounded the intruder alarm. But because of faulty wiring, the wrong alarm went off: instead, the klaxon announcing an incoming Soviet nuclear warhead began its apocalyptic wah-wah. Everyone on the base had been told there would be no drills at a time like this. The ashen men manning the station went ahead: they began the chain reaction of retaliation against Moscow.

It was only at the last second that the sentry got through to the station. It was a mistake, he cried — just a bear, growling at the fence. If he had made that call five minutes later, you wouldn’t be reading this article now.

I have been thinking about that bear recently, because there has just been a string of startling security lapses in the British and American nuclear arsenals. In the past year alone, a truck carrying a fully-assembled nuclear weapon has skidded off the road in Wiltshire and crashed, while six nuclear warheads were lost by the US military for 36 hours.

A new documentary called Deadly Cargo, recently premiered in Glasgow, documents a simple and extraordinary fact: every week, fully assembled Weapons of Mass Destruction are driven along the motorways and byways of Britain. Britain’s nuclear submarines are up in Scotland, while the factories that need to test and replenish them are down in Reading — so they are shuttled between them all the time in large green trucks that are followed a half-mile behind by decontamination units. It slipped on ice and crashed not long ago.

The film shows how a group of brave protesters called NukeWatch have been able to figure out the exact route of the convoy and track it. One of them explains, “You reach out on the motorway and they’re an arm’s length from you. That’s how close the British public come to nuclear weapons.” If they could work it out, couldn’t other groups with uglier motives do the same?

Leaked documents from the Ministry of Defence show them fretting that an attack on the convoy “has the potential to lead to damage or destruction of a nuclear warhead within the UK” and “considerable loss of life”.

More amazingly still, Britain’s weapons do not have a secret launch code. They can be fired or detonated by the commander in charge of them simply by opening them up manually and turning some switches and buttons. Every other nuclear power has an authorisation code known only to the country’s leader, which has to be read out to the soldiers in charge of the weapon before it can be used. Not us. Whenever the British government has tried to introduce this basic safety procedure, the Navy has got huffy and refused to participate, saying it is “tantamount” to claiming their officers are not “true gentlemen”.

The Navy dismiss the risk of a hijacking, or a Doctor Strangelove situation where a navy commander goes nuts. But the latter has almost happened. In 1963, a US B-47 bomber crew guarding a nuclear bomb discovered that one of their colleagues had broken all the seals, removed all the safety wires, and turned on the pilot’s readiness switch and the navigator’s control switch on the nuclear bomb. The man seemed to be going through a bout of insanity.

In the US, an even-more startling nuclear lapse occurred last summer: bombs with the force of 60 Hiroshimas were simply lost by the military. On 29 August, a group of US airmen accidentally attached six nuclear warheads to their plane, mistaking them for unarmed cruise missiles intended for a weapons graveyard. They were then flown across the continental United States and left, unwatched by anyone, on an airstrip in Louisiana. Nobody even noticed they were gone for more than a day. This is not, it seems, a freak event: the Air Force’s inspector general found in 2003 that half of the “nuclear surety” inspections conducted that year were failures. Yes, that’s half.

This is what we know is happening in relatively orderly and open societies. There have almost certainly been incidents in China and North Korea and Pakistan that we will never hear about — until the worst happens.

The dangers of any individual nuclear accident are, of course, very small — but small risks of massive death, accumulating over the 60 years of the nuclear age, suddenly don’t look so negligible any more. Those who campaign for a reduction in the number of nuclear weapons are often referred to as utopian, or naïve. In fact, it is utopian to believe we can carry on like this without an explosion sooner or later.

So it is disturbing that the number of nuclear weapons in the world may be about to dramatically increase. Not in Iran, where (thankfully) sanctions seem to be working, but in Russia and China. The Bush administration, backed by the British government, has been insisting for more than 20 years on building a “nuclear shield” that would, in theory, shoot down any incoming nuclear weapons before they struck the US and its allies. After more than $100bn of military-industrial bungs, the technology still doesn’t work, but they are pushing on with it anyway. Russia and China have been pleading for a treaty that would prevent it because they want to retain the existing balance of power — but the Bush administration has flatly refused.

The result? China and Russia are now saying they will significantly increase their nuclear weapon production. It is, they insist, the only way to ensure they would be able to punch through the US missile shield and so retain some parity with US power.

The more weapons, the more likely an accident — or worse. But when the world should be scaling down the number of nukes, the Bush administration is actually ensuring they are ramped up.

Almost unnoticed in the Presidential race, Barack Obama has proposed the US recommit itself to moving towards a world without nukes. This isn’t out-of-the-blue: his best work as a Senator has been trying to lock up Russia’s barely guarded old weapons — while Bush tried to slash the funding for it. Some 66 per cent of the US public support the zero-nukes goal. Yet Hillary Clinton has been bragging about her ability to “obliterate” Iran instead, while McCain has cheered on the Bush shield-madness. There is no popular movement to pressure them into sanity.

Without the careful multilateral dismantling of these weapons, thousands of them will remain scattered across the earth, waiting — waiting for an accident with a bear, or a hijacked convoy, or a flipped-out submarine commander. Precisely how many nuclear near-death experiences do you want to risk?

Johann Hari writes for The Independent.