American countries except El Salvador and Argentina, resulting in the Act of Chapultepec of 6 March 1945. The Act included a framework for the negotiation of a regional security treaty. It also shaped Latin American pressure during the United Nations conference in San Francisco for clauses in the UN Charter to facilitate regional collective defense, under Article 51. Initially, the security conference was planned to be held in Rio de Janeiro in late 1945 or early 1946; however, disputes between the United States and Argentina's Juan Domingo Perón (President from 4 June 1946) led to delays. The United States and some Latin American concern about peronismo raised the possibility of including collective intervention to preserve democracy in the security conference. During the delay, global tensions between the United States and Soviet Union grew. In light of the developing Cold War and following the statement of the Truman Doctrine on 12 March 1947, the United States wished to make those new anti-communist commitments permanent, as did many anti-communist leaders in Latin America. History Signing The Inter-American Treaty of Reciprocal Assistance was the first of many so-called "mutual security agreements", and the formalization of the Act of Chapultepec. The treaty was adopted by the original signatories on 2 September 1947 in Rio de Janeiro (hence the colloquial name "Rio Treaty"). It came into force on 3 December 1948 and was registered with the United Nations on 20 December 1948. With the exceptions of Trinidad and Tobago (1967) and the Bahamas (1982), no countries that became independent after 1947 have joined the treaty; Canada is yet to become a member, though it already has separate defense commitments with the United States. Cold War Though the Cold War overtones of the Rio Treaty became increasingly evident, during the immediate post-war years, Long argues that it was more closely tied to pre-WWII regional antecedents and, even, Latin American diplomatic pressure. Long states, "Despite many Latin American concerns about the United States’ ultimately interventionist nature, Latin American diplomats cited the Monroe Doctrine and United States-led Pan-Americanism in support of a grand bargain that would extend and institutionalize U.S. engagement while restricting unilateralism." However, the United States' often considered adherence to the Treaty's principles of nonintervention as secondary to its Cold War concerns. Decline As revolutionary and nationalist governments spread through Latin America through the 1950s and 1960s, the fear of a shared enemy that was experienced