Final answer:
The incorrect reason for the internment of Japanese Americans during WWII is that an espionage network had been uncovered. Internment was actually based on racial prejudice, war hysteria, and a failure of political leadership, and no Japanese Americans were found guilty of espionage or sabotage.
Step-by-step explanation:
The United States government interned over 100,000 Japanese Americans during WWII for all of the following reasons except: d. FBI and military intelligence had uncovered a Japanese American espionage network in California.
In fact, during World War II, no evidence was found of a Japanese American espionage network; instead, internment was fueled by race prejudice, war hysteria, and the failure of political leadership. This policy of mass exclusion and detention affected over 110,000 Japanese and Japanese-descended individuals, of which seventy thousand were American citizens. After the war, a congressional commission and numerous historical records asserted that there had been no valid security reasons for such mass internment, and those interned were not found guilty of espionage or sabotage. Ultimately, President Reagan signed an Act that formally apologized for the internment and provided reparations to surviving internees.