Leading article: The shadow of the bomb still lingers after 60 years

This week, Iran threatened to break off negotiations with the European Union and restart its nuclear processing plant in Isfahan. The European Union - represented by Britain, France and Germany - has, in turn, threatened to take the country to the United Nations Security Council for breaching the 1968 Nuclear Non-Proliferation Treaty.

This is by no means the only nuclear dispute confronting the world. The United States and four other nations are engaged in sensitive negotiations with North Korea in an attempt to persuade that bankrupt Asian regime to destroy its nuclear weapons. The governments of South Korea and Japan are particularly concerned about what this unstable dictatorship might be capable of. Japan is even considering what was once unthinkable - developing its own nuclear deterrent.

There is one encouraging sign. Pakistan and India - two nuclear-armed nations - appear to have reached an accommodation on minimising the prospect of a catastrophic war on the subcontinent. There are plans for a hotline between the Indian and Pakistani foreign ministries to avoid misunderstandings. But it would be wrong to draw too much comfort from this. Pakistan's government is far from secure. There is a real danger that General Musharraf could be deposed by Islamist militants, who would have little interest in peace with India. And the two nations are still in profound dispute over Kashmir.

It is also necessary to take into consideration the stockpiles of nuclear weapons that exist in the unstable states of the former Soviet Union. Security experts have been warning since the early 1990s that there is a serious danger these could find their way into the hands of terrorists. This becomes an even greater threat in the era of al-Qa'ida.

What makes a bad situation worse is the double standards exhibited by the long-established nuclear powers. It is, of course, right that the international community is attempting to persuade North Korea to disarm, and Iran not to go down the nuclear route. But those nations that are at the forefront in calling for smaller countries to disarm have made no efforts to live up to their own obligations under the Non-Proliferation Treaty. All nations are supposed to be diminishing their stockpiles of nuclear weapons. Yet the United States and Russia have done little on this front. Indeed, President Bush has given the green light to the development of "battlefield" nuclear weapons. Israel refuses even to confirm whether it has such weapons or not. And our own Prime Minister is on the verge of sanctioning an upgrade of Britain's Trident defence system. It is little wonder that the pariah nations of the world detect hypocrisy when powerful countries come to demand that they eschew nuclear technologies.

We have entered a new age of global instability, less predictable than the Cold War. Unless the entire world makes serious efforts to destroy its nuclear weapons we are in grave danger of seeing the terrors of Hiroshima and Nagasaki repeated in our own lifetimes.