A noiseless flash. With those few words in the New Yorker in 1946, John Hersey captured the power of a nuclear explosion.

Hollywood has since earned buckets of money with popular movies that imagine nuclear armageddon and its desolate aftermath.

Yet many people despair that the story that actually belongs in the realm of science-fiction is the idea of a world free from the threat of nuclear war. That after more than 60 years of campaigning, the dream of total nuclear disarmament seems no closer to becoming reality.

Or has something changed?

US President Barack Obama, confronted by a bewildering array of economic challenges at home, has added to his already burdened agenda. He has outlined hopes to reduce the nuclear arsenal around the globe and cast fatalism as a deadly adversary: "for if we believe that the spread of nuclear weapons is inevitable, then in some way we are admitting to ourselves that the use of nuclear weapons is inevitable,'' he said.

"Generations lived with the knowledge that their world could be erased in a single flash of light,'' he told an audience in Europe earlier this year. But even though the Cold War stand-off between the US and Soviet Union had ended, in a strange turn of history, the risk of a nuclear attack had gone up.

"More nations have acquired these weapons. Testing has continued. Black market trade in nuclear secrets and nuclear materials abound. The technology to build a bomb has spread. Terrorists are determined to buy, build or steal one. Our efforts to contain these dangers are centred on a global non-proliferation regime, but as more people and nations break the rules, we could reach the point where the centre cannot hold.''

He promised to renew efforts towards disarmament.

Many American leaders have spoken about the threat of nuclear weapons. But what set Obama's remarks apart from those in recent times was a crucial acknowledgement - a recognition that while even one country holds a nuclear weapon, others will aspire to obtain one.

"We can't reduce the threat of a nuclear weapon going off unless those who possess the most nuclear weapons - the United States and Russia - take serious steps to actually reduce our stockpiles,'' he said. The once bitter enemies have pledged to negotiate a reduction in their nuclear warhead.

This is the principle at the heart of the nuclear Non-Proliferation Treaty, the instrument signed in 1968 and credited with helping to limit the spread of nuclear weapons. The parties to the treaty - 189 countries in all - agree to forgo atomic bombs in return for the right to develop peaceful nuclear energy. Only five countries are allowed nuclear weapons under the treaty; the US, Russia, Britain, France and China. Each in turn agreed to pursue "good faith'' talks on nuclear disarmament.

It's a sound bargain, Obama has agreed. Yet as former Australian prime minister Paul Keating put it recently, the treaty has so far turned out to be "perhaps the most egregious example of international double dealing of any international regime'' - the nuclear weapons states have not only kept their weapons, they have made new ones too. A recent study put the 2008 cost of maintaining the US nuclear weapons program at $52 billion.

The failure of the great powers to destroy their nuclear arsenals has in part given impetus for those few countries outside the treaty to develop the bomb; Israel, India, Pakistan and North Korea. Other nations, such as Iran and Syria, are suspected of harbouring nuclear ambitions. Obama pledged to strengthen the international framework so that any country who breaks the rules will face consequences.

"Words must mean something,'' he said.

But it will take time to judge whether the president intends to subject America to the rules and relinquish its own nuclear arsenal. "This goal will not be reached quickly - perhaps not in my lifetime,'' he said. "It will take patience and persistence.''

And in the meantime, the other nuclear powers must agree to surrender their weapons too - including those pariahs from international agreements.

Efforts to tackle the nuclear threat are again gearing up. The Australian and Japanese government's have launched a major study into the non-proliferation treaty to suggest areas to improvement ahead of a review conference in 2010. The treaties committee of federal parliament, chaired by Melbourne MP Kelvin Thomson, is also undertaking an inquiry, and earlier this year heard a bleak assessment of the future.

''We are also now in what is being referred to as the nuclear renaissance,'' said former US Senator Bob Graham. ``In the next 10 years from now, the largest nuclear states in the world will be Russia, United States, followed by China, Pakistan and India.''

Pakistan alone had tripled its number of nuclear weapons over the past five years, he said, and was likely to double that again in the next five.

''That is an extremely dangerous development and one that commands the world's attention,'' Graham said, adding the objective must be finding a way to eventually eradicate nuclear weapons.

``If Australia were to lead the way in that, cheers.''

But the biggest expectations rest with the man in the Oval Office, the president who must be prepared to decide whether to press his finger to the button.

''There are those who hear talk of a world without nuclear weapons and doubt whether it's worth setting a goal that seems impossible to achieve,'' he mused.

''But make no mistake: We know where that road leads ... To denounce or shrug off a call for cooperation is an easy but also a cowardly thing to do. That's how wars begin. That's where human progress ends.''

Under a mushroom cloud.