In September 1940, with the permission of the pro-Nazi Vichy government of France, Japan moved into northern French Indochina, establishing a foothold in strategically important Southeast Asia. A few days later, Japan signed a mutual defense agreement, the Tripartite Pact, with Germany and Italy, putting it on a collision course with the United States. The German invasion of the Soviet Union in June 1941 relieved the Japanese of the Soviet threat in East Asia. As a result, in July 1941 Japan decided to move its troops into southern French Indochina for possible operations against the oil-rich Netherlands Indies. The United States responded by freezing Japanese assets in the United States and imposing an oil embargo on Japan. Britain, the Commonwealth of Nations countries, and the government of the Netherlands Indies quickly followed suit, cutting 90 percent of Japan's oil imports. Faced with a choice of submitting to United States demands for a return to the pre-1931 status quo or confronting the United States, Japan determined to strike out boldly. Beginning with a devastating attack against the United States fleet at Pearl Harbor, Hawaii, on December 7, 1941, it quickly took advantage of superior air and naval power to occupy the Philippines, the Netherlands Indies, Malaya, and Singapore. An overland offensive brought Burma and Thailand under Japanese control, and a string of amphibious operations established Japan's control of the South Pacific. By mid-1942 Japanese forces appeared to be in control of most of their objectives (see fig. 2).
It was at this point that the superior economic and industrial power of the United States began to turn the tide. In June 1942, the Japanese directed the bulk of their navy to Midway, a tiny atoll at the northern tip of the Hawaiian chain, expecting to destroy the rest of the United States Pacific fleet. Instead, the United States, forewarned of the attack, used carrier-based aircraft to devastate the Japanese fleet. The United States counteroffensive had begun. In the South Pacific, after six months of heavy fighting, Japanese forces evacuated Guadalcanal in February 1943. From there, revitalized United States and Allied forces retook most of the South Pacific islands occupied by the overextended Japanese forces. By June 1944, United States and Allied forces had reached Saipan, in the Mariana Islands, putting their bombers within range of the Japanese homeland.
When United States air, ground, and sea power began to reverse the tide of Japanese victories, the authority of the Japanese forces began to wane in the captured territories. At home in Japan, however, respect remained high until intensive United States aerial bombardment there raised popular doubt about the military's ability to win the war. It was not until the last days of the war, after the United States had dropped atomic bombs on Hiroshima and Nagasaki, that the emperor, in an unprecedented political act, compelled the general staff to accept the terms for surrender.
Data as of January 1994