The present basic philosophy is nuclear deterrence.
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.
When the START 2 treaty has been implemented - and remember it has not yet been ratified - we will be left with some 15,000 nuclear warheads, active and in reserve. Fifteen thousand weapons with an average yield of 20 Hiroshima bombs.
This means that the only function of nuclear weapons, while they exist, is to deter a nuclear attack.
But the first the general public learned about the discovery was the news of the destruction of Hiroshima by the atom bomb. A splendid achievement of science and technology had turned malign. Science became identified with death and destruction.
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.
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.
Indeed, the very first resolution of the General Assembly of the United Nations - adopted unanimously - called for the elimination of nuclear weapons.
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.
All nuclear weapon states should now recognize that this is so, and declare - in Treaty form - that they will never be the first to use nuclear weapons. This would open the way to the gradual, mutual reduction of nuclear arsenals, down to zero.
The chief task was to stop the arms race before it brought utter disaster. However, after the collapse of communism and the disintegration of the Soviet Union, any rationale for having nuclear weapons disappeared.
Long before the terrifying potential of the arms race was recognized, there was a widespread instinctive abhorrence of nuclear weapons, and a strong desire to get rid of them.
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.
We are told that the possession of nuclear weapons - in some cases even the testing of these weapons - is essential for national security. But this argument can be made by other countries as well.
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.
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.
My third appeal is to my fellow citizens in all countries: Help us to establish lasting peace in the world.
I appeal to my fellow scientists to remember their responsibility to humanity.
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.
Indeed, the whole human species is endangered, by nuclear weapons or by other means of wholesale destruction which further advances in science are likely to produce.