The biggest reason why Italians and Germans weren’t rounded up was that the Nazi and Italian fascists didn’t use kamikaze attacks as a military strategy.
The Japanese were interned long before the kamikaze attacks started.
Most of the Japanese in Hawaii were NOT interned at all——most of the Mainland ones were.
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Neither did the Japanese until the closing months of the war.
There was an internment camp about 20-30 miles from my hometown in SE Arkansas. I never heard one word about it until someone on FR mentioned it then I looked into it. That was the one Mr. Solo’s family was interned in.
The inmates had better living conditions than the people in the surrounding area: indoor plumbing, good heat, fresh water and good food. That was not acceptable.
Interment was probably for the protection of the Japanese from an enraged populace as much as to protect the nation.