We are probably in danger from a few hundred people out of a few million, mainly young men.
In WW2, Americans born with the first names Fritz and Heinrich probably didn’t get well-paid jobs in armament factories.
However, they weren’t generally deported. My father’s uncle worked for a police department in New York State. His job starting in the late 1930’s was to deal with overactive Germans in his American city.
If Obama’s executive branch functioned properly, the killer wouldn’t have been able to buy the guns.
I suspect the divorce records are very informative.
Residents and visitors who have visas or green cards are not Americans. Americans shouldn’t be deported, of course. Non citizens, well, that’s another matter entirely.