Hitler's reasons for declaring war against the US were numerous. One was an emotional response: the Japanese tactic of using a surprise attack without making a declaration of war appealed to him – he had done the same thing when he attacked the Soviet Union with Operation Barbarossa in June 1941; indeed, he told the Japanese ambassador "[O]ne should strike – as hard as possible – and not waste time declaring war."[1] Also, the prospect of a worldwide war fed Hitler's tendency towards grandiose thinking, and reinforced his feeling that he was a world-historical figure of destiny. As he said in his declaration speech to the Reichstag: