The article presents the perceptions of Russia and Japan during the dispute about the areas of influence in the Far East and the Russo-Japanese War by the American authorities and society in the period from January to September 1904. The American government’s position and the public opinion were presented on the basis of selected reports from the Russian ambassador to the USA, Arthur Cassini. They allow for a statement to be made that both before and during the initial phase of the conflict, Americans sympathised with Japan. Apparently, this resulted from the pragmatic approach taken by the American government, as well as from the activity of Japanese diplomats, thanks to which American press published information that was favourable for the Japanese and disadvantageous for Russia. However, when Japan gained advantage in the conflict, the feeling slowly shifted. The grounds for this was that the American public became aware of the threat to American industry and trade, related to Japan’s reinforced position in the Far East. It may also be observed that excessive weakening of Russia and strengthening of Japan at its expense did not correspond with the idea of global balance of power and the concept of the appurtenant spheres of influence, advocated by the president of the United States, Theodore Roosevelt.