On the other hand, the guy who was actually in charge of domestic security and counter-espionage wrote regarding Japanese-Americans:
“Every complaint in this regard has been investigated, but in no case has any information been obtained which would substantiate the allegation.”
FBI Director J. Edgar Hoover has been accused of a lot of things, but he was never accused of being a softy when it came to national security. And Hoover opposed mass incarceration in concentration camps. The sentiment of people at the time reflects how traumatic Pearl Harbor was, how atrocious the behavior of the Japanese military government was, how effective war propaganda was, and how bad race relations were. Popular sentiment was not informed by the actual threat of sabotage or espionage by fellow citizens. There simply wasn’t any tangible evidence nor were there any instances of sabotage or espionage.