There is a real important aspect of the WW II internments that has been mostly forgotten but was relevant in the extreme at the time. The Japanese internees were corralled by and large for their own protection. Many were not rounded up particularly if they had a farm, were more or less rural, and the neighbors vouched for them as being productive. I saw the protection aspect in my own family. While she had no grief with Japanese in particular my Chicksaw Grandmother would have killed the next one she saw if anything had happened to one of my uncles who were serving in the Pacific. In those years most Japanese still had connections in Japan, still spoke at least some Japanese, and were still more “Japanese” than “American.”
Scalia is absolutely correct that if America is once more attacked by a more or less homogeneous foreign group resident members of that group will very likely be rounded up. A whole bunch of Americans might lose their senses of humor after another such event and otherwise just start cleaning house.
The entire community of Florin (east of Sacramento) was rounded up and they were all productive farmers.
WADR, if it didn't happen after 9-11, when a million dead Muslims would have been a good start, it's not likely to happen at all.