The United States had been warned in advance that there would be a surprise attack on Pearl Harbor. They had also broken all Japanese codes and were aware of all the details needed to prevent the attack on Pearl Harbor. Roosevelt had made a campaign promise to not get involved in a war with Germany unless the United States was attacked first; so, he made strategic use of Japan’s plans as a way to go to war with Germany. The FBI was warned by one of Britain’s top agents, Duskov Popov, about a planned attack on Pearl Harbor and that it would be soon. The FBI told him that the information was too precise and too complete to be true. They assumed it was a trap since the information detailed exactly where, when, how, and by whom the United States was going to be attacked. Both Churchill's secret envoy and head of secret service failed to convince the US government to take Popov seriously. In the fall of 1941, Kilsoo Haan, an agent for the Sino-Korean People's League, told Eric Severeid of CBS that the Korean underground had proof that the Japanese were going to attack Pearl Harbor before Christmas. In addition, one Korean had even seen the plans. In late October, Haan finally convinced US Senator Guy Gillette that the Japanese were planning to attack in December or January, and he alerted the State Department and Army and Navy Intelligence, but it was soon discarded. Haan called Maxwell Hamilton at the State Department in December, and told him that the Korean underground had information that the Japanese would attack Pearl Harbor the coming weekend. He also forwarded a written report pointing to the publication of Hawaiian Air Corps schedules for November and December by the Japanese paper Nippu JiJi. On November 19th, the Americans intercepted a word code that established a series of messages to be inserted into the daily weather forecasts of Tokyo Radio. The British decrypted "Higashi No Kaze Ame" on November 25th. The phras...