Let me remind you that nuclear disarmament is not just an ardent desire of the people, as expressed in many resolutions of the United Nations. It is a legal commitment by the five official nuclear states, entered into when they signed the Non-Proliferation Treaty.
At a time when science plays such a powerful role in the life of society, when the destiny of the whole of mankind may hinge on the results of scientific research, it is incumbent on all scientists to be fully conscious of that role, and conduct themselves accordingly.
I did not imagine that the second half of my life would be spent on efforts to avert a mortal danger to humanity created by science.
The most terrifying moment in my life was October 1962, during the Cuban Missile Crisis. I did not know all the facts - we have learned only recently how close we were to war - but I knew enough to make me tremble.
But scientists on both sides of the iron curtain played a very significant role in maintaining the momentum of the nuclear arms race throughout the four decades of the Cold War.
Since the end of the Cold War two main nuclear powers have begun to make big reductions in their nuclear arsenals. Each of them is dismantling about 2,000 nuclear warheads a year.
So I ask the nuclear powers to abandon the out-of-date thinking of the Cold War period and take a fresh look. Above all, I appeal to them to bear in mind the long-term threat that nuclear weapons pose to humankind and to begin action towards their elimination.
The Cold War is over but Cold War thinking survives.
There is no direct evidence that nuclear weapons prevented a world war. Conversely, it is known that they nearly caused one.
This is the reality of nuclear weapons: they may trigger a world war; a war which, unlike previous ones, destroys all of civilization.
As for the assertion that nuclear weapons prevent wars, how many more wars are needed to refute this arguments? Tens of millions have died in the many wars that have taken place since 1945.
But the nuclear powers still cling tenaciously to their weapons.
The decision to use the atom bomb on Japanese cities, and the consequent buildup of enormous nuclear arsenals, was made by governments, on the basis of political and military perceptions.
I have to bring to your notice a terrifying reality: with the development of nuclear weapons Man has acquired, for the first time in history, the technical means to destroy the whole of civilization in a single act.
The time has come to formulate guidelines for the ethical conduct of scientist, perhaps in the form of a voluntary Hippocratic Oath.