Okay, had never heard the story of interned German Americans but I was able to find that approximately 11,000 (“overwhelmingly, German nationals”) were held by the federal government. This is out of 1.2 million German-born immigrants in the US at that point, in addition to about another 30-35 million Americans of German descent. 114,000 Germans immigrated to the US in the 1930’s to escape Nazi Germany. No doubt there may have been a few spies in that group. I’m sure the vast majority of the 11,000 held were innocent.
As for Italian Americans, about 1,900 recent immigrants with no US citizenship were interned by the US government during the war. Another 600,000 Italian immigrants were not detained. And millions of Italian-American citizens were left alone.
As for the Japanese Americans, 120,000 of the 127,000 living in the continental US were sent to “concentration camps”. 62% of the Japanese who were interned were US citizens. Anyone with at least 1/16th Japanese blood was considered eligible for detention. It is considered a racist action and not a security action. A different standard for them versus those of German or Italian descent.