An authoritarian military dictatorship ruled Chile for seventeen years, between 11 September 1973 and 11 March 1990. The dictatorship was established after the democratically-elected socialist government of Salvador Allende was overthrown in a coup d'état backed by the United States on 11 September 1973. During this time, the country was ruled by a military junta headed by General Augusto Pinochet. The military used the breakdown of democracy and the economic crisis that took place during Allende's presidency to justify its seizure of power. The dictatorship presented its mission as a "national reconstruction." The coup was the result of multiple forces, including pressure from conservative groups, certain political parties, union strikes and other domestic unrest, as well as international factors. The regime was characterized by the systematic suppression of political parties and the persecution of dissidents to an extent unprecedented in the history of Chile. Overall, the regime left over 3,000 dead or missing, tortured tens of thousands of prisoners, and drove an estimated 200,000 Chileans into exile. The dictatorship's effects on Chilean political and economic life continue to be felt. Two years after its ascension neoliberal economic reforms were implemented, in sharp contrast to Allende's leftist policies, advised by a team of free-market economists educated in US universities known as the Chicago Boys. Later, in 1980, the regime replaced the Chilean Constitution of 1925 with a new constitution in a sham referendum. This established a series of provisions that would eventually lead to the 1988 Chilean national plebiscite on October 5 of that year. In that plebiscite, 55% of voters rejected the proposal of extending Pinochet's presidency for another eight years. Consequently, democratic presidential and parliamentary elections were held the following year. The military dictatorship ended in 1990 with the election of Christian-Democrat candidate Patricio Aylwin. However, the military remained out of civilian control for several years after the junta itself had lost power. Rise to power There has been a large amount of debate over the extent of US government involvement in destabilising the Allende government. Recently declassified documents show evidence of communication between the Chilean military and US officials, suggesting covert US involvement in assisting the military's rise to power. Some key figures in the Nixon administration, such as Henry Kissinger, used the Central Intelligence Agency (CIA) to mount a major destabilization campaign. As the CIA revealed in 2000, "In the 1960s and the early 1970s, as part