investigation on Japanese Americans living on the West Coast and in Hawaii. After working with FBI and ONI officials and interviewing Japanese Americans and those familiar with them, Munson determined that the "Japanese problem" was nonexistent. His final report to the President, submitted November 7, 1941, "certified a remarkable, even extraordinary degree of loyalty among this generally suspect ethnic group." A subsequent report by Kenneth Ringle (ONI), delivered to the President in January 1942, also found little evidence to support claims of Japanese-American disloyalty and argued against mass incarceration. After Pearl Harbor The surprise attack on Pearl Harbor on December 7, 1941, led military and political leaders to suspect that Imperial Japan was preparing a full-scale invasion of the United States West Coast. Due to Japan's rapid military conquest of a large portion of Asia and the Pacific including a small portion of the U.S. West Coast (i.e., Aleutian Islands Campaign) between 1937 and 1942, some Americans feared that its military forces were unstoppable. American public opinion initially stood by the large population of Japanese Americans living on the West Coast, with the Los Angeles Times characterizing them as "good Americans, born and educated as such." Many Americans believed that their loyalty to the United States was unquestionable. However, six weeks after the attack, public opinion along the Pacific began to turn against Japanese Americans living on the West Coast, as the press and other Americans became nervous about the potential for fifth column activity. Though the administration (including President Franklin D. Roosevelt and FBI Director J. Edgar Hoover) dismissed all rumors of Japanese-American espionage on behalf of the Japanese war effort, pressure mounted upon the administration as the tide of public opinion turned against Japanese Americans. Although the impact on US authorities is controversial, the Niihau incident immediately followed the attack on Pearl Harbor, when Ishimatsu Shintani, an Issei, and Yoshio Harada, a Nisei, and his Issei wife Irene Harada on the island of Ni'ihau violently freed a downed and captured Japanese naval airman, attacking their fellow Ni'ihau islanders in the process. Several concerns over the loyalty of ethnic Japanese seemed to stem from racial prejudice rather than any evidence of malfeasance. The Roberts Commission report, which investigated the Pearl Harbor attack, was released on January 25 and accused persons of Japanese ancestry of espionage leading up to the attack. Although the report's key finding was that General Walter