In 1945 the United States saw the Soviet Union as its principal ally. By 1947, it saw the Soviet Union as its principal opponent. How did this happen? Historian John Lukacs has provided an answer to this question through an exchange of letters with George F. Kennan. Their correspondence deals with the antecedents of containment between 1944 and 1946, during most of which time Kennan was at the American embassy in Moscow. Kennan had strong opinions about America's appropriate role during and after World War II and is perhaps best known as the architect of America's containment policy. Much has been written about Kennan and containment, but relatively little is known about the events that made him compose and send the Long Telegram in 1946 that ultimately became the draft for foreign policy dealing with the Soviets in the following forty years. These letters show Kennan's fear of the extent to which the United States misunderstood the Soviet regime. Especially in 1944, at the time of the Russians' betrayal of the Warsaw Uprising, it became evident that the Soviets were interested in establishing their rigid domination of Eastern and Central Europe and dividing the continent. Kennan's letters to Lukacs are thorough and detailed, suggesting that the Truman administration was not in the least premature in opposing the Soviet Union. Indeed, both correspondents suggest that these decisions should have been made earlier. This series of letters will add greatly to our understanding of what preceded containment and the Cold War in 1947.