Japanese spies were a real threat, same as Ebola. Question then and now was/is do you quarantine innocent people because they may be a threat to others? Most of the Japanese Americans were innocent. Most of the quarantined Ebola workers are disease free. Where do you draw the line between safety and stepping on rights?
Check here for a list and description of some of the Japanese spies in action during WW2. List of Japanese spies, 1930
Check here for a list and description of some of the Japanese spies in action during WW2. List of Japanese spies, 1930