The government consolidated its popularity among the peasants through land reform, which included the execution of between 1 and 2 million landlords. China developed an independent industrial system and its own nuclear weapons. The Chinese population increased from 550 million in 1950 to 900 million in 1974. However, the Great Leap Forward, an idealistic massive reform project, resulted in an estimated 15 to 35 million deaths between 1958 and 1961, mostly from starvation. In 1966, Mao and his allies launched the Cultural Revolution, sparking a decade of political recrimination and social upheaval that lasted until Mao's death in 1976. In October 1971, the PRC replaced the Republic in the United Nations, and took its seat as a permanent member of the Security Council.