Japans relationship with the US in world war 2?

Relations between the US and Imperial Japan were icy in the years before the official start of WW 2 in 1939. The US and the rest of the "free world " were disturbed by the Japanese invasion of China in 1931. Of course after the 1941 surprise Japanese attack on Pearl Harbor, the two nations were at war with one another in the Pacific theater. Only after the effects of the atomic bomb drops in August of 1945 did the Emperor and his top commanders agree to an unconditional surrender.