Honouliuli National Monument preserves the history of the largest and longest-used confinement site during World War II. Run by the U.S. army, the internment camp held approximately 400 internees and 4,000 prisoners of war. The majority of the internees were Japanese Americans who were American citizens by birth, but suspected of disloyalty to the United States after Pearl Harbor was attacked by the Japanese military. By the end of WWII, approximately 2,000 people of Japanese descent from Hawaii were interned, none of which were found guilty of sabotage, espionage, or any other charges against the United States. Those that were not Japanese Americans were predominantly German Americans although there were also some Americans of Italian, Irish, Russian, and Scandinavian descent. It was discovered by volunteers from the Japanese Cultural Center of Hawaii in 2002.