I don't pretend to know the true causes of any war still less WWII - reasons for war are always complex and engineered by small groups of people acting mostly out of self interest - who, apart from powerful American interests, ever wanted to invade Iraq/Afghanistan? Roosevelt had his eye on Japan for some time prior to the outbreak of WWII in Europe (if I'm not mistaken?) though he stepped up the pressure once it had started. He also hated the British Empire, he wanted to see it dismantled and he got his wish with Britain bankrupt at the end of the war. He also detested Churchill, more than once referring to him as a drunk. in fact when you look at the wartime meetings of Roosevelt, Stalin, and Churchill he appears more friendly towards Stalin than Churchill, referring to him as "Uncle Joe" while Churchill was seething.
It doesn't help in understanding the causes of war by the history being written by the victors.
