Why was the japanese american a threat to civilians in america? (u. s. histor/give full description! )

''Significantly, the incarceration program got underway despite a warning; in January 1942, a naval intelligence officer in Los Angeles reported that Japanese-Americans were being perceived as a threat almost entirely “because of the physical characteristics of the people.” Fewer than 3 percent of them might be inclined ...''

He did that to war with groups