The internment of Italian Americans refers to the government's internment of Italian nationals in the United States during World War II. As was customary after Italy and the US were at war, they were classified as "enemy aliens" and some were detained by the Department of Justice under the Alien and Sedition Act. But in practice, the US applied detention only to Italian nationals, not to US citizens, or long-term US residents. Italian immigrants had been allowed to gain citizenship through the naturalization process during the years before the war, and by 1940 there were millions of US citizens who had been born in Italy.