<P> The Japanese attack on Pearl Harbor coupled with their alliance with the Nazis and the ensuing war in the Pacific fueled anti-Japanese sentiment, racism, xenophobia, and anti-Axis sentiment in the Allied nations like never before . Japanese, Japanese - Americans and Asians having a similar physical appearance were regarded with deep seated suspicion, distrust and hostility . The attack was viewed as having been conducted in an extremely underhanded way and also as a very "treacherous" or "sneaky attack". Suspicions were further fueled by the Niihau Incident, as historian Gordon Prange stated "the rapidity with which the three resident Japanese went over to the pilot's cause" which troubled the Hawaiians . "The more pessimistic among them cited the Niihau Incident as proof that no one could trust any Japanese, even if an American citizen, not to go over to Japan if it appeared expedient ." </P> <P> The attack, the subsequent declarations of war, and fear of "Fifth Columnists" resulted in internment of Japanese, German, and Italian populations in the United States and others, for instance the Japanese American internment, German American internment, Italian American internment, and Japanese Canadian internment . The attack resulted in the United States fighting the Germans and Italians among others in Europe and Japan in the Pacific . </P> <P> The consequences were world - changing . Prime Minister Winston Churchill knew that the survival of the British Empire depended on American aid, and since 1940 had frequently asked Roosevelt to declare war . Churchill aide John Colville stated that the prime minister and American Ambassador John Gilbert Winant, who also supported the British, "sort of danced around the room together" as the United States would now enter the war, making a British victory likely . Churchill later wrote, "Being saturated and satiated with emotion and sensation, I went to bed and slept the sleep of the saved and thankful ." </P> <P> By opening the Pacific War, which ended in the unconditional surrender of Japan, the attack on Pearl Harbor lead to the breaking of an Asian check on Soviet expansion . The Allied victory in this war and the subsequent U.S. emergence as a dominant world power, eclipsing Britain, have shaped international politics ever since . </P>

When did the us attack japan after pearl harbor