During WW2 black American soldiers were put into segregated, all black units. Was the same true for Asians and Native Americans or were they just put into units alongside whites?
To elaborate on what has been said, the 442nd Regimental Combat Team became one of the most decorated units of the war. As an all Japanese-American unit, many of the soldiers had family held in Japanese’s Internment camps during their service. While the unit consisted of primarily enlisted Japanese-Americans, most of the officers of the 442nd were Caucasian.
There were no segregated Native American units during the war. However, as a result of many of the men of the 45th Infantry Division being from Arizona, Colorado, New Mexico and Oklahoma, a large portion of the division was composed of Native Americans from many different tribes. As segregated as it got for Native Americans would probably be Company C, 180th Infantry, 45th Division, which formed at Chilocco Indian School and contained over two hundred Native American men from over fifty different tribes. However, as the war went on, outfits like Company C of the 180th became integrated with Caucasian replacements who fought alongside the Native American soldiers without complaint.
James M. McCaffrey, Going For Broke: Japanese American Soldiers in The War Against Nazi Germany.(Norman, Oklahoma: University of Oklahoma Press, 2013).
Flint Whitlock, The Rock of Anzio: From Sicily to Dachau, A History of the 45th Infantry Division.(Boulder, Colorado: Westview Press, 1998).
Native Americans, particularly the Navajo for their famous code talking, would often fight alongside white soldiers. I'm not aware of any segregated units for Native Americans.
Asians rarely fought in the Pacific War unless they had a special role or a tactically useful one (for obvious reasons - they resembled the enemy). However in Europe, they did indeed serve in segregated units as well.