One can say a little more about the effects of scientific and technological discoveries on the relations among the people of the globe. With added discoveries raw materials will no longer be needed with the old urgency. For most substances substitutes are being found. This may make for greater economic independence. On the other hand, new possibilities will present themselves. We shall learn how to control the air and how to cultivate the oceans. This will call for cooperation and more interdependence. The dangers from radioactive by-products will act in a similar direction. The radioactive cloud released from a reactor accident may be more dangerous than a nuclear explosion. Such a cloud will not stop at national boundaries. Some proper form of international responsibility will have to be developed. What effect the existence of nuclear weapons will have upon the coexistence of nations is a question less understood and less explored than any other affecting our future. Most people turn away from it with a feeling of terror. It is not easy to look at the question with calm reason and with little emotion. A few predictions seem disturbing but are highly probable: Nuclear secrets will not keep. Knowledge of nuclear weapons will spread among nations—at least as long as independent nations exist. Prohibition will not work. Laws or agreements which start with the word “don’t” can be broken and will always be broken. If there is hope, it must lie in the direction of agreements which start with the word “do.” The idea of “Atoms for Peace” succeeded because it resulted in concrete action. An all-out nuclear war between the major powers could occur but we may have good hope that it will not occur if we remain prepared to strike back. No one will want to provoke the devastation of his own country. Atomic bombs may be used against cities. But there will be no military advantage in destroying cities. In a short and highly mobile war neither centers of supply and communication nor massive means of production will count. If cities are bombed, this will be done primarily for reasons of psychological warfare. We must be and we are prepared for this kind of war but only as a measure of retaliation. There is good reason to believe that as long as we are prepared for all-out war, our civilian population will not suffer from a nuclear attack. The certainty of a counterblow gives real protection against all-out war. No such protection exists against wars limited in territory and in aims. In the history of mankind such wars have been most frequent. There is no indication that these limited wars have ended. We must be prepared for these conflicts with effective and mobile units, and this requires the use of nuclear firepower. Nuclear weapons will certainly have a profound effect upon such limited warfare. Not all of this effect need be and indeed it must not be in the direction of greater devastation.