If an agreement were made to discontinue the tests, the United States would surely keep such an agreement. The very social and political structure of our country excludes the possibility that many people would collaborate in breaking an international undertaking. Whether Russia would or would not keep such an agreement would depend on the ingenuity of the Russians, on their willingness to make economic sacrifices, and on their honesty. Of these three factors we can have a firm opinion about the first. The Russians are certainly ingenious enough to devise secret methods of testing. As to the other questions, whether the Russians will want to invest the effort and whether they will be bound by their word, we feel that each man is entitled to his own opinion. According to past experience, an agreement to stop tests may well be followed by secret and successful tests behind the iron curtain. In a more general way we may ask the question: Is it wise to make agreements which honesty will respect, but dishonesty can circumvent? Shall we put a free, democratic government at a disadvantage compared to the absolute power of a dictatorship? Shall we introduce prohibition in a new form, just to give rise to bootlegging on a much greater scale? It is almost certain that in the competition between prohibition and bootlegging, the bootlegger will win. All of these arguments, however, would become irrelevant if it were true that further testing would not accomplish any further desirable result. It has been said and often repeated that we now possess adequate nuclear explosives to wipe out the cities of any enemy. What more do we need? Our main purpose in further experimentation with nuclear bombs is not, of course, to make city-busters more horrible. We would prefer not to have to use our nuclear weapons at all. We keep them as a counterthreat against the danger that we ourselves should be subjected to a devastating attack. To understand what we are actually trying to do in the tests, we have to take a closer look at some military problems. In the Second World War strategic bombing was used for the first time on a really massive scale. It may well be and, in fact, it is probable that such strategic bombing will not be repeated in the future. There are two military reasons for the bombing of cities. One is that factories are located in cities, and these factories support the war effort. The other reason is that cities are centers of transportation through which the supplies of war materials pass. By destroying these centers the flow of the war supplies can be interrupted.