Here is a senario. Japan lets Germany know that it is to attack Pearl Harbour as retribution for the sanctions imposed upon it by the USA due to Japanese war in China, but Fuhrer Adolf Hitler needs Japan to open up a second front for "Barbarossa" and convinces the Japanese to cancel its attack on Hawaii. Japan shocks the world by announcing that it is withdrawing the bulk of it forces from China and that China and Japan sign the Sino-Nipponese accord which Japanese troops will remain in North China and Inner Mongolia in which China will recognise and that Shang-Kai Shek (sic) agrees to sign the Anti-Comintern Pact. The USA withdraws its sanctions on Japan. So no attack on any US soil, either Hawaii or Philipines or any US flagged ships are sunk, so how does the US get into the war by by-passing its neutrality act. So what it the consequences of the war in Europe with no US involement. And that the Soviet Union fighting on a two front war.