Answer:
because the Japanese bombed pearl harbor
Step-by-step explanation:
While there were Germans Italians in the USA they did not prove a threat to Americans and nether did the Japanese but the when japan launched the sneak attack on pearl harbor many Americans thought that the Japanese people could start turmoil on American soil which if done would be devastating. so they decided not to take chances and stop and capture Japanese people. even though there was Nazi Germany they attacked Europe not USA.
hope this helped