Koremastu and other Japanese Americans were put into internment camps because Japan attacked the United States at Pearl Harbor and this triggered a huge anti-japanese movement in the USA. The internment is considered to have resulted more from racism than from any security risk posed by Japanese Americans.Those who were as little as 1/16 Japanese and orphaned infants with "one drop of Japanese blood" were placed in internment camps.
Simple Answer: Because they were Japanese.
