- Japan emerged as a world power toward the end of the 19th century and confirmed its position with the defeat of the Imperial Russian fleet in 1904. Theodore Roosevelt helped mediate the peace settlement in Portsmouth, New Hampshire, in 1905, and he also agreed to the Japanese imposition of a protectorate over Korea. A balance of power between the United States and Japan in the Pacific and the “Open Door” policy guaranteeing China’s territorial integrity was agreed in the Root-Takahira Agreement of 1907. However, by the 1930s a nationalistic and militaristic government had assumed power in Japan and it embarked on an expansionist policy in pursuit of raw materials and national aggrandizement, starting in 1931 with the invasion of Manchuria. In 1933, Japan left the League of Nations and in July 1937 invaded China.The U.S. reaction to Japanese aggression was first to call for Japan to be “quarantined” and then to exert economic pressure, to which the Japanese responded with further expansion, occupying French Indochina (Vietnam, Laos, Cambodia) in 1940 and 1941 and announcing a New Order in Asia. The U.S. embargo on the export of scrap metal and aviation fuel in 1940 was followed by the freezing of Japanese assets in the United States in July 1941. Japan signed a Tripartite Pact with Germany and Italy on 27 September 1940 promising mutual support in the event of war with the United States, and in October 1941 the hard-line war minister, General Hideki Tojo, assumed power. Tojo was prepared to go to war if the United States did not resume trade relations, while the Roosevelt administration, through Cordell Hull, called first for an end to expansion in China and then in November 1941 insisted on withdrawal. Facing war, the Japanese launched a surprise air attack on the U.S. fleet in Pearl Harbor on Sunday morning, 7 December 1941. This attack brought the United States into World War II.After initially seeming unstoppable, Japan was gradually overcome by a combination of naval defeats in the battles of the Coral Sea, Midway, and Leyte Gulf, combined with the fierce “island hopping” campaign culminating with the invasions of Iwo Jima and Okinawa in 1945. However Japan surrendered only after the dropping of the atomic bombs on Hiroshima and Nagasaki on 6 and 9 August 1945. Emperor Hirohito then insisted that the government accept the peace terms laid down by the Allied powers at the Potsdam Conference, and the formal surrender was signed aboard the USS Missouri on 2 September 1945. General Douglas MacArthur assumed control of the Allied occupation forces in Japan on 14 August 1945, and Japan was forced to accept political and economic reforms. On 8 September 1951, the United States and 48 other nations signed a final peace treaty with Japan in San Francisco, bringing the war to an end. The treaty was ratified by the U.S. Senate on 20 March 1952.
Historical Dictionary of the Roosevelt–Truman Era . Neil A. Wynn . 2015.