Letter from Mr Attlee to President
Truman, 25 September 1945
Dear Mr President
Ever since the USA demonstrated to the world the terrible effectiveness of the atomic bomb I have been increasingly aware of the fact that the world is now facing entirely new conditions. Never before has there been a weapon which can suddenly and without warning be employed to destroy utterly the nerve centre of a great nation. The destruction wrought by the Germans through their air fleet on Warsaw and Rotterdam was startling enough, but subsequent attempts to do the same to London were defeated, though without much to spare. Our own attacks on Berlin and the Ruhr resulted in the virtual destruction of great centres of industry. In Europe the accumulated material wealth of decades has been dissipated in a year or two, but all this is not different in kind from what was done in previous wars in Europe during the Dark Ages and the Thirty Years War, in America by your own civil war. Despite these losses civilisation continued and the general framework of human society and of relations between peoples remained. The emergence of this new weapon has meant, taking account of its potentialities, not a quantitative but a qualitative change in the nature of warfare.
Before its advent military experts still thought and planned on assumptions not essentially different from those of their predecessors. It is true that the conservative (with a small c!) mentality tended to maintain some of these although they were already out of date. For instance we found at Potsdam that we had to discuss a decision taken at the Crimea Conference as to the boundaries of Poland. These were delimited by rivers although the idea of a river as a strategic frontier has been out of date ever since the advent of air warfare. Nevertheless, it was before the coming of the atomic bomb not unreasonable to think in terms of strategic areas and bases, although here again it has seemed to me that too little account has been taken of the air weapon.
Now, however, there is in existence a weapon of small bulk capable of being conveyed on to a distant target with inevitable catastrophic results. We can set no bounds to the possibilities of airplanes flying through the stratosphere dropping atomic bombs on great cities.