World War II ended in September 1945 with the Surrender of Japan, and relations with the USSR became a central matter of foreign policy. Various issues, including the fate of European and Asian postwar governments and the administration of the United Nations, had already begun to strain the wartime alliance between the Soviet Union and the United States. Critics of the USSR objected to the oppressive satellite states it had established in Eastern Europe and Soviet involvement in the Greek Civil War and the Chinese Civil War. In February 1946, George F. Kennan laid out the doctrine of containment, which called for the United States to resist the spread of Communism. Wallace feared that confrontational policies towards the Soviet Union would eventually lead to war, and urged Truman to "allay any reasonable Russian grounds for fear, suspicion, and distrust". Historian Tony Judt wrote in "" that Wallace's "distaste for American involvement with Britain and Europe was widely shared across the political spectrum".