In World War II the Soviet Union, the United Kingdom, and the United States joined together to fight the Axis Power in Europe and in the Pacific. Prior to the war the United States had been isolationist for one hundred and fifty years. When the war ended the Unites States had demobilized its forces, and the country looked forward to peace, and a balanced budget. However, within eighteen months of the end of the war the Truman administration had convinced the Americans that they had to be prepared for perpetual war. How could the population accept this radical turn and accept challenges to their freedoms, and the establishment of a near garrison state, with atomic war possible at any time? This thesis examines what was said at the wartime conferences, analyzes the proposed peace agreements, and examines the information available to Roosevelt and Truman. A comparison is made to the public pronouncements vs. the private statements of Roosevelt and Truman to determine if the country had been misled about the actual chances for long tem peace after the war. The result of the thesis is the conclusion that Roosevelt had led foreign policy by himself, had disregarded the State Department, and had an irrational view of Stalin's peaceful goals from the time he established diplomatic relations with the Soviet Union in 1933 - to the time of his death in April 1945.As early as 1943 at the wartime conference in Tehran the West indicated that Stalin could have a sphere of influence in Eastern Europe. At Yalta, in 1945, Roosevelt expressed his lack of interest in European affairs and failed to get a precise declaration on the future of Poland. His public addresses had assured Americans that the liberated countries would have the right to democratic elections, but he and Churchill had acknowledged in secret that the Soviet Union would oversee Eastern Europe. These facts were obtained by dissecting the records of the people who attended the conferences and who had to make foreign policy by following the president's decisions. Other primary sources were the Truman Library, The Franklin D. Roosevelt Library and Museum, the CIA, the State Department and the American Embassy. The conclusion is that the secret agreements at the war conferences, and the lack of precision in what was supposed to happen in the liberated countries, left room for the Soviet Union to gradually assimilate all those countries. The Cold War occurred because while the Grand Alliance was in effect the West did not press Stalin for the democratic goals that the citizens of America and the United Kingdom thought would take effect. The American and British people suffered great hardships and loss of life for the avowed goal of establishing democratic ideals around the world. In short time Stalin declared that Communism and capitalism could not co-exist. The Long Telegram by George Kennan and the Clifford Elsey Report in 1946 determined that the Soviets wanted world domination, the elimination of capitalist states, and subversion and aggression against the West. In April 1947 The Truman Policy was pronounced and it put America on a permanent war footing, and called for business, education and science to unite to fight the terror of Communism. It also established that the United States would be the policeman for the world. The American people did not know that by 1945 the seeds of the Cold War were planted because the West capitulated to Stalin, consequently, when they heard that the homeland was being threatened, they abandoned over one hundred fifty years of isolation and accepted the national security state. Americans had been misled throughout the war, and the acceptance of perpetual war and the possible use of atomic weapons resonated with the country because the whole world now had to face the Communist threats.