We had no alternative, then, but to press on, to probe the secrets of atomic power to the uttermost of our capacity, to maintain, if we could, our initial superiority in the atomic field.  At the same time, we sought persistently for some avenue, some formula, for reaching an agreement with the Soviet rulers that would place this new form of power under effective restraints—­that would guarantee no nation would use it in war.  I do not have to recount here the proposals we made, the steps taken in the United Nations, striving at least to open a way to ultimate agreement.  I hope and believe that we will continue to make these efforts so long as there is the slightest possibility of progress.  All civilized nations are agreed on the urgency of the problem, and have shown their willingness to agree on effective measures of control—­all save the Soviet Union and its satellites.  But they have rejected every reasonable proposal.

Meanwhile, the progress of scientific experiment has outrun our expectations.  Atomic science is in the full tide of development; the unfolding of the innermost secrets of matter is uninterrupted and irresistible.  Since Alamogordo we have developed atomic weapons with many times the explosive force of the early models, and we have produced them in substantial quantities.  And recently, in the thermonuclear tests at Eniwetok, we have entered another stage in the world-shaking development of atomic energy.  From now on, man moves into a new era of destructive power, capable of creating explosions of a new order of magnitude, dwarfing the mushroom clouds of Hiroshima and Nagasaki.

We have no reason to think that the stage we have now reached in the release of atomic energy will be the last.  Indeed, the speed of our scientific and technical progress over the last seven years shows no signs of abating.  We are being hurried forward, in our mastery of the atom, from one discovery to another, toward yet unforeseeable peaks of destructive power.

Inevitably, until we can reach international agreement, this is the path we must follow.  And we must realize that no advance we make is unattainable by others, that no advantage in this race can be more than temporary.

The war of the future would be one in which man could extinguish millions of lives at one blow, demolish the great cities of the world, wipe out the cultural achievements of the past—­and destroy the very structure of a civilization that has been slowly and painfully built up through hundreds of generations.

Such a war is not a possible policy for rational men.  We know this, but we dare not assume that others would not yield to the temptation science is now placing in their hands.

With that in mind, there is something I would say, to Stalin:  You claim belief in Lenin’s prophecy that one stage in the development of communist society would be war between your world and ours.  But Lenin was a pre-atomic man, who viewed society and history with pre-atomic eyes.  Something profound has happened since he wrote.  War has changed its shape and its dimension.  It cannot now be a “stage” in the development of anything save ruin for your regime and your homeland.