SEVENTY years ago tomorrow the world had its first experience of the terrible power of nuclear weapons. The USA obliterated Hiroshima with an atomic bomb. Three days later, as if to confirm that the technology worked, it did the same to Nagasaki. Japan surrendered the following day, ending the Second World War.

Since then, the world had kept the lid on this potentially most destructive of tinder boxes. Or rather it hasn’t – quite. For while the lid has never been blown off by an explosion, it has been raised to more than replenish the use of those first two atomic bombs. There are now 16,000 nuclear weapons spread around the world. And the USA, as the original sole possessor, has been joined by eight other nations.

Some people believe that the threat of “mutually assured destruction” posed by nuclear weapons has maintained peace between the superpowers, thereby preventing a third world war. Maybe it has. But how realistic is it to suppose that this will always be the case? Or that a nuclear weapon will not one day fall into the hands of terrorists, who wouldn’t hesitate to use it? Or that some dreadful mistake might unleash one?

Of these scenarios, a superpower nuclear war might seem the least likely. But there are worrying signs, certainly from Russia, that the possible use of nuclear weapons is being normalised. Earlier this year the Russian ambassador to Demark warned that if the country joined Nato’s missile defence, “Danish warships will be targets for Russian nuclear missiles.” Since then, President Putin has announced that Russia will be putting 40 new nuclear-armed intercontinental missiles into service. Russian military pundits have actually called for a nuclear strike on the United States. Who can doubt that if either superpower was losing a “conventional” war against the other, the nuclear option would be triggered?

Let us recall some facts about Hiroshima. The bomb killed around 100,000 people instantly, that number quickly doubling. People up to four miles away felt the heat and blast, which brought down buildings. And yet the bomb was only about a twentieth as powerful as a current version. The old Soviet Union detonated a bomb 3,000 times more powerful.

Have we been fooling ourselves all these years – believing the lid could be kept on forever? Just as gunpowder became universal, it is inevitable more nations will go nuclear. Maintaining the security of not only weapons but bomb-grade material will become ever-more daunting. The Hiroshima explosion was produced by a mere seven-tenths of a gram of enriched uranium – barely the weight of a cheque. It seems idle to think none will ever be smuggled out for terrorism.

For the most part though we prefer to ignore the increasing possibility of a nuclear holocaust. The Hiroshima anniversary should turn our minds to it. Among the survivors, aged five at the time, is a lady who, after decades of silence, speaks publicly of her experiences. In her dreams she still sees ghastly scenes seared into her infant’s mind. “Being at peace is the happiest and most precious thing for humankind,” she says.

But true peace, founded on goodwill not fear, has always evaded humankind. And not even the likelihood that one day we will blow ourselves and our civilisation to bits has brought it any closer.