Debates over the use of atomic bombs on the Japanese cities of Hiroshima and Nagasaki have been active for decades and continue to this day. The chronology of events and the available evidence are consistent with the idea that President Truman's most compelling reason to authorize the use of atomic weapons was for diplomatic and political reasons, with an eye toward the Soviet Union, rather than to end before the war with the immediate surrender of Japan. The development of the atomic bomb was the largest secret scientific research program ever undertaken. There are several reasons given to justify the use of the bomb. There are, however, a number of proven factors that call this perspective into question. An aggressive Soviet Union in Eastern Europe and Asia made it clear that they would become a threat to Britain and the United States. President Truman, informed of the alternatives, chose to use the bomb, recognizing that it would be an important diplomatic tool in dealing with the Soviets. The world was at war. Germany, controlled by Adolf Hitler, dominated much of Europe. It had mainly been Britain's war, until June 1941, when the Nazis invaded the Soviet Union. In the Far East, Japan continued its imperialistic expansion having already occupied Korea, Manchuria and the major cities of China. In 1940, Japan aligned itself with the Axis powers of Nazi Germany and Italy, led by fascist dictator Benito Mussolini. The fall of France to the Germans in 1940 allowed Japan to control previously held territories in Southeast Asia, including Vietnam. In response to Japanese aggression, the United States imposed an embargo on vital resources needed for Japan's war efforts. On December 7, 1941, Japan attacked American military bases in Hawaii, devastating... middle of paper... sing. Trinity Day. New York: Athenaeum, 1965. McKain, Mark. Creation and use of the atomic bomb. San Diego, CA: Greenhaven, 2003. Rhodes, Richard. The making of the atomic bomb. New York: Simon & Schuster, 1986. Stimson, Henry. Diary of Henry Stimson. 14-15 May 1945. Personal account. Sterling Library, Yale University, New Haven.Stimson, Henry. Diary of Henry Stimson. April 25, 1945. Personal account. Sterling Library, Yale University, New Haven.Sullivan, Edward T. The Ultimate Weapon: The Race to Develop the Atomic Bomb. New York: Holiday House, 2007.Truman, Harry S. Memoirs of Harry S. Truman: Year of Decisions (vol. 1). New York: Doubleday, 1955. Weintraub, Stanley. The Last Great Victory: The End of World War II, July/August 1945. New York: Truman Talley /Dutton, 1995.Zhukov, Georgiĭ Konstantinovich. Memoirs of Marshal Zhukov. New York: Delacorte, 1971.