Comecon supplied aid to the eventually victorious Chinese Communist Party, and its influence grew elsewhere in the world. Fearing its ambitions, the Soviet Union's wartime allies, the United Kingdom and the United States, became its rivals. In the ensuing Cold War, the two sides clashed indirectly in several proxy wars. De-Stalinization and Khrushchev Thaw (1953–1964) Stalin died on 5 March 1953. Without a mutually agreeable successor, the highest Communist Party officials initially opted to rule the Soviet Union jointly through a troika headed by Georgy Malenkov. This did not last, however, and Nikita Khrushchev eventually won the ensuing power struggle by the mid-1950s. In 1956, he denounced Joseph Stalin and proceeded to ease controls over the party and society. This was known as de-Stalinization. Moscow considered Eastern Europe to be a critically vital buffer zone for the forward defence of its western borders, in case of another major invasion such as the German invasion of 1941. For this reason, the USSR sought to cement its control of the region by transforming the Eastern European countries into satellite states, dependent upon and subservient to its leadership. As a result, Soviet military forces were used to suppress an anti-communist uprising in Hungary in 1956. In the late 1950s, a confrontation with China regarding the Soviet rapprochement with the West, and what Mao Zedong perceived as Khrushchev's revisionism, led to the Sino–Soviet split. This resulted in a break throughout the global Marxist–Leninist movement, with the governments in Albania, Cambodia and Somalia choosing to ally with China. During this period of the late 1950s and early 1960s, the USSR continued to realize scientific and technological exploits in the Space Race, rivaling the United States: launching the first artificial satellite, Sputnik 1 in 1957; a living dog named Laika in 1957; the first human being, Yuri Gagarin in 1961; the first woman in space, Valentina Tereshkova in 1963; Alexei Leonov, the first person to walk in space in 1965; the first soft landing on the Moon by spacecraft Luna 9 in 1966; and the first Moon rovers, Lunokhod 1 and Lunokhod 2. Khrushchev initiated ‘The Thaw’, a complex shift in political, cultural and economic life in the country. This included some openness and contact with other nations and new social and economic policies with more emphasis on commodity goods, allowing a dramatic rise in living standards while maintaining high levels of economic growth. Censorship was