The presidency of Harry S. Truman began on April 12, 1945, when Harry S. Truman became President of the United States upon the death of Franklin D. Roosevelt, and ended on January 20, 1953. Relations with the Soviet Union declined after 1945, and by 1947 the two countries had entered a period of geopolitical tension known as the Cold War. After top aide Clark Clifford rewrote and toned down the speech, Truman delivered a speech calling for Congress to pass a new law to draft all the railroad strikers into the army.