By the end of the Second World War, the Soviet Union and the United States emerged as global superpowers. The ensuing deterioration of relations between the Soviet-backed Eastern Bloc and U.S.-backed Western Bloc gave rise to a sustained period of tensions known as the Cold War that lasted until 1989. In the final years of his leadership, Stalin presided over the post-war reconstruction of the Soviet Union as well as the development of a Soviet atomic bomb in 1949. During these years, the country experienced another major famine and an antisemitic campaign that culminated in the doctors' plot. After Stalin's death in 1953, he was eventually succeeded by Nikita Khrushchev, who subsequently denounced his rule and initiated the de-Stalinisation of Soviet society.