The author analyses the changes in Chinese policy of the USA after the outbreak of the Second World War. During the interwar period the U.S. policy in China was the policy of minimal risk therefore in 1930s the USA only morally condemned the Japanese actions in Asia and did not provide substantial assistance to China. In 1941 the situation changed. The USA headed for the rendering of economic and military aid to China. After the Japanese attack on Pearl Harbor the coordination of joint military operations in East and South-East Asia came out on top in the U.S. policy in China.