Stalin's government promoted Marxism–Leninism abroad through the Communist International and supported European anti-fascist movements during the 1930s, particularly in the Spanish Civil War. In 1939, it signed a non-aggression pact with Nazi Germany, resulting in the Soviet invasion of Poland. Germany ended the pact by invading the Soviet Union in 1941. Despite initial setbacks, the Soviet Red Army repelled the German incursion and captured Berlin in 1945, ending World War II in Europe. The Soviets annexed the Baltic states and helped establish Soviet-aligned governments throughout Central and Eastern Europe, China, and North Korea. The Soviet Union and the United States emerged from the war as global superpowers. The tensions that arose between the Soviet-backed Eastern Bloc and U.S.-backed Western Bloc became known as the Cold War. Stalin led his country through the post-war reconstruction, during which it developed a nuclear weapon in 1949. In these years, the country experienced another major famine and an antisemitic campaign peaking in the doctors' plot. After Stalin's death in 1953, he was eventually succeeded by Nikita Khrushchev, who denounced him and initiated the de-Stalinisation of Soviet society.