Closer to midnight
When the devastation of the atomic bombs dropped on the Japanese cities of Hiroshima and Nagasaki 60 years ago became apparent, two opinions formed - such weapons should never be used again and more were needed.
A tug of war has since ensued, with nuclear-weapons advocates making the most gains but groups pushing for their elimination at times making significant inroads.
The cold war between the US and the former Soviet Union sparked an arms race that by the 1980s had produced a global nuclear arsenal of 60,000 weapons and brought the world to the brink of conflict. That threat receded with the collapse of the Soviet Union in 1989 and stockpiles have since been halved.
But whether the world is safer now from a nuclear attack is debatable as more nations acquire nuclear weapons and there is the risk they could fall into terrorists' hands. As alarmingly for non-proliferation activists, another arms race looms with some of the world's nine nuclear powers considering an end to test bans and resuming production.
For the deputy director of the Hiroshima Peace Memorial Museum, Takafumi Sotowada, it is a gloomy situation. The US dropped the world's first atomic bomb used in warfare on the city on August 6, 1945. The museum and peace park were set up to remember the 140,000 victims, and to advocate the elimination of nuclear weapons. His assessment is based on the number of countries seeking nuclear weapons and the inability of a New York conference in May to revise the Non-Proliferation Treaty (NPT), enacted in 1970. 'The world is not safer from the threat of nuclear warfare,' he said. 'There are countries like North Korea and Iran that are trying to seek the power they believe they acquire by possessing nuclear weapons. We are concerned that we are facing the threat of proliferation.'
The NPT, with 187 of the world's 191 countries as signatories, obligates the acknowledged nuclear powers - Britain, China, France, Russia and the US - not to transfer weapons or technology and other members not to acquire or produce arms. Cuba, India, Israel and Pakistan have not signed. Cuba has no nuclear weapons. North Korea, which withdrew from the pact, claims to have them, while Iran is accused of trying to start a programme.
Stein Tonnesson, director of the International Peace Research Institute in Oslo, agreed the nuclear threat was greater now than in the cold war. While the internet can be partly to blame, the activities of the 'father' of Pakistan's nuclear programme, Abdul Qadeer Khan, have also contributed. He acknowledged in 2003 having helped Libya's nuclear programme, which was revealed and dismantled in 2002, and admitted passing information to Iran, among others. As if such revelations were not shocking enough for those lobbying nuclear powers to scrap their arms, US President George W. Bush last month reversed decades of US and international non-proliferation policy by lifting a ban on co-operation with India.
The regions most at risk of being caught up in a nuclear conflict extend in an 'arc of crisis' from the Middle East, through South Asia to northeast Asia comprising countries with unresolved disputes - Israel and Iran, India and Pakistan, China and India and North Korea and the US.
Convincing nations to give up their nuclear weapons or their desire to acquire them could not be resolved quickly, warned Joseph Cirincione, director of the Carnegie Endowment for International Peace's non-proliferation programme. The co-author of Deadly Arsenals: Tracking Weapons of Mass Destruction, said getting Iran to give up its nuclear ambitions meant dealing with its security concerns over Israel. In turn, Israel's fears about its Arab neighbours also had to be resolved. 'That's hard, but it's a lot easier to do that than to deal with what will happen if nothing is done - a Middle East with three or four nuclear states,' he said.
A country could never be convinced to give up nuclear weapons while another continued to have thousands of them. Creating such an approach was also being hampered by decisions like those made by Mr Bush towards India, which he called a major mistake that 'blows a huge hole through the international norm against the spread of these weapons'.
But the professor of national security studies at New Delhi's Centre for Policy Research, Bharat Karnad, applauded the strategy, claiming it would neutralise the possibility of nuclear conflict with India's rivals, China and Pakistan. Nuclear weapons, he said, were a deterrent and brought stability, not war.
What Mr Bush's decision - made without congressional approval - means for the Doomsday Clock, the Bulletin of the Atomic Scientists' barometer of the global nuclear threat, will not be known until its September issue. At present, it stands at seven minutes to midnight, the same as in 1980, when the deadlock in US and Soviet arms talks deepened and nationalistic wars and terrorism increased; 1968, when China and France acquired nuclear weapons and wars raged in the Middle East, Indian subcontinent and Vietnam; and 1960, as a freeze in the cold war began with the crisis between the US and Cuba.
At the height of the cold war in 1984, the clock stood at three minutes to midnight. Only once before had it been considered closer to a nuclear conflict - in 1953, when the testing by the US and Soviet Union within a nine-month period prompted scientists to set the minute hand two minutes off midnight.
North Korea and Iran did not overly worry experts, who believed that deals could be struck to convince them to give up their nuclear ambitions. Of greater concern was the possibility of terrorists getting a bomb, the accidental launching of one of the thousands of missiles the US and Russia have aimed at each other, or increased proliferation.
The cold war's end ushered in a new era of peace, and the US, Russia, Britain and France began scrapping stockpiles. Testing and production bans were put in place. American nuclear physicist Charles Ferguson, the Council on Foreign Relations' science and technology fellow, said the 12-year-old moratorium of the US on testing was being strained by Bush administration plans for new weapons.
Most of the US nuclear stockpile comprised high-yield weapons and there was now a perceived need for less powerful bombs, Dr Ferguson said. Known as 'bunker-busters' and 'mini-bombs', they could be used to destroy underground weapons caches or the command posts of adversaries.
Then there is the problem of the early warning security systems of the US and Russia. The room for error is great. In January 1995 Russian president Boris Yeltsin came within minutes of launching bombs at a Norwegian scientific rocket mistaken for an American missile. 'There's not much more than 15 or 20 minutes to make a decision. Computer glitches and the like could cause an accidental war. The nuclear weapons need to be taken off alert to give a lot of time - hours or days - before systems can actually be used,' Dr Ferguson said.
Asked if the world was now safer than during the cold war, he was undecided. That the Soviet Union no longer existed and the US and Russia were on friendlier terms reduced the risk of a thermonuclear war, he suggested. But the possibility of an accident remained, North Korea and Iran loomed large on the radar and, after the September 11 terrorist attacks, there was the threat of extremists obtaining and using nuclear weapons. 'We're less safe from a nuclear explosion than during the cold war,' Dr Ferguson said.
Dr Cirincione believes otherwise. 'What we're really worried about now is terrorists' use of nuclear weapons,' he said. 'As horrible as it would be to lose a city in an atomic cataclysm, it is a threat many orders removed from what we faced every day during the cold war.'
Sixty years after the second world war ended with 210,000 deaths in atomic blasts over Hiroshima and Nagasaki, the world is still locked in debate about whether to keep or scrap the most dangerous weapons ever developed.
1947 Cold war: 7 minutes to midnight
1949 Soviet Union tests first atomic bomb: 3 minutes
1953 US and Soviets test nuclear devices: 2 minutes
1963 US and Soviets sign partial test-ban treaty: 12 minutes
1968 France and China test nuclear weapons, wars in Middle East, Indian subcontinent and Vietnam:
1969 US Senate ratifies Nuclear Non-Proliferation Treaty: 10 minutes
1972 US and Soviets sign arms and missiles limitation treaties: 12 minutes
1974 India tests its 'Peaceful Nuclear Explosive', known as Smiling Buddha: 9 minutes
1980 Deadlock in US-Soviet talks, wars and terrorism: 7 minutes
1981 Arms race escalates and conflicts rage: 4 minutes
1988 US-Soviet treaty to eliminate intermediate nuclear forces: 6 minutes
1990 Fall of Berlin Wall: 10 minutes
1991 US and Soviets sign Strategic Arms Reduction Treaty: 17 minutes
1995 Military spending stays at cold war levels: 14 minutes
1998 India and Pakistan test nuclear weapons and US-Russia stockpile reduction hits difficulties: 9 minutes
2002 US rejects arms control treaties and plans to quit missile treaty; terrorists try to get nuclear weapons: 7 minutes