In San Francisco on 20 March 1941, Tatsuta Maru disembarked Colonel Hideo Iwakuro dispatched by Prime Minister Hideki Tojo to assist Ambassador Admiral Kichisaburo Nomura in his negotiations with the United States. On 26 July, President Franklin D. Roosevelt signed an executive order to seize Japanese assets in the United States in retaliation for the Japanese invasion of French Indochina. Tatsuta Maru was in San Francisco at the time, and American authorities confiscated a shipment of over nine million dollars in bonds by the Yokohama Specie Bank. On 30 July, the American government granted Tatsuta Maru a license to purchase enough fuel oil for the voyage back to Japan. This was last official oil export from the United States to Japan before the start of World War II. On the return voyage to Japan, the ship was struck with a case of food poisoning in which 125 passengers were affected, of which eight died. One of the stricken passengers was Susumu Nikaido, the post-war vice-president of the LDP. The incident was the subject of an essay by Yuriko Miyamoto.
