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United States involvement

The United States opposition to Allende started several years before he was elected President of Chile. Declassified documents show that from 1962 to 1964, the CIA spent $3 million on anti-Allende propaganda "to scare voters away from Allende's FRAP coalition" and spent a total of $2.6 million to finance the presidential campaign of Eduardo Frei.

The possibility of Allende winning Chile's 1970 election was deemed a disaster by the Nixon administration that wanted to protect American geopolitical interests by preventing the spread of Communism during the Cold War. In September 1970, then United States president Richard Nixon informed the CIA that an Allende government in Chile would not be acceptable and authorized $10 million to stop Allende from coming to power or unseat him. A CIA document declared, "It is firm and continuing policy that Allende be overthrown by a coup." Henry Kissinger 's 40 Committee and the CIA planned to impede Allende's investiture as President of Chile with covert efforts known as "Track I" and "Track II"; Track I sought to prevent Allende from assuming power via so-called "parliamentary trickery", while under the Track II initiative, the CIA tried to convince key Chilean military officers to carry out a coup.

Some point to the involvement of the Defense Intelligence Agency agents that allegedly secured the missiles used to bombard La Moneda Palace. In fact, open US military aid to Chile continued during the Allende administration, and the national government was very much aware of that although there is no record that Allende himself believed that such assistance was anything but beneficial to Chile. During Richard Nixon 's presidency, United States officials attempted to prevent Allende's election by financing political parties aligned with opposition candidate Jorge Alessandri and supporting strikes in the mining and transportation sectors. After the 1970 election, the Track I operation attempted to incite Chile's outgoing president, Eduardo Frei Montalva, to persuade his party (PDC) to vote in Congress for Alessandri.

Under the plan, Alessandri would resign his office immediately after assuming it and call new elections. Eduardo Frei would then be constitutionally able to run again (since the Chilean Constitution did not allow a president to hold two consecutive terms, but allowed multiple non-consecutive ones), and presumably easily defeat Allende. The Chilean Congress instead chose Allende as president, on the condition that he would sign a "Statute of Constitutional Guarantees" affirming that he would respect and obey the Chilean Constitution and that his reforms would not undermine any of its elements. Track II was aborted, as parallel initiatives already underway within the Chilean military rendered it moot. During the second term of office of Democratic President Bill Clinton, the CIA acknowledged having played a role in Chilean politics before the coup, but its degree of involvement is debated. The CIA was notified by its Chilean contacts of the impending coup two days in advance but contends it "played no direct role in" the coup.

Much of the internal opposition to Allende's policies came from the business sector, and recently released United States government documents confirm that the United States indirectly funded the truck drivers' strike, which exacerbated the already chaotic economic situation before the coup. The most prominent United States corporations in Chile before Allende's presidency were the Anaconda and Kennecott copper companies and ITT Corporation, International Telephone and Telegraph. Both copper corporations aimed to expand privatized copper production in the city of Sewell in the Chilean Andes, where the world's largest underground copper mine "El Teniente", was located.

At the end of 1968, according to United States Department of Commerce data, United States corporate holdings in Chile amounted to $964 million. Anaconda and Kennecott accounted for 28% of United States holdings, but ITT had by far the largest holding of any single corporation, with an investment of $200 million in Chile. In 1970, before Allende was elected, ITT owned 70% of Chitelco, the Chilean Telephone Company and funded El Mercurio, a Chilean right-wing newspaper. Documents released in 2000 by the CIA confirmed that before the elections of 1970, ITT gave $700,000 to Allende's conservative opponent, Jorge Alessandri, with help from the CIA on how to channel the money safely. ITT president Harold Geneen also offered $1 million to the CIA to help defeat Allende in the elections.

After General Augusto Pinochet assumed power, United States Secretary of State Henry Kissinger told President Nixon that the United States "didn't do it" (referring to the coup) but "we helped them... created the conditions as great as possible". Recent documents declassified under the Clinton administration 's Chile Declassification Project show that the United States government and the CIA sought to overthrow Allende in 1970 immediately before he took office (" Project FUBELT "). Many documents regarding the United States intervention in Chile remain classified. Those that have been declassified showed that Nixon, Kissinger, and the United States government were aware of the coup and the plans to overthrow Allende's democratically elected government.