During World War 2 the American government decided to send all persons of Japanese descent into concentration camps, this included American Citizens. These camps were in no way as bad as Nazi Concentration camps but people were still imprisoned without having committed any crime. Even though they were some of the most loyal, productive citizens, they had ancestors from the Japan and that was enough to indict them. German and Italian citizens who were not American citizens were also sent to internment camps.
American Citizens of German and Italian descent, however were not sent to these camps, mainly because they registered low on the melanin count, ie their skins were white. In the '80s the government apologized and gave Japanese Americans, reparations.