You mean in this ATL, the US would get the OAS to resolve that "The purpose of this [Communist] offensive is the destruction of democratic institutions and the establishment of totalitarian dictatorships at the service of extra-continental powers." and "That adherence by any member of the Organization of American States to Marxism–Leninism is incompatible with the inter-American system and the alignment of such a government with the communist bloc breaks the unity and solidarity of the hemisphere"?
http://avalon.law.yale.edu/20th_century/intam17.asp
OK, that wasn't until 1962 and was a reaction to Castro's Cuba. So let's go back to 1954:
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Whereas:
The American republics at the Ninth International Conference of American States declared that international communism, by its antidemocratic nature and its interventionist tendency, is incompatible with the concept of American freedom and resolved to adopt within their respective territories the measures necessary to eradicate and prevent subversive activities;
The Fourth Meeting of Consultation of Ministers of Foreign Affairs recognized that, in addition to adequate internal measures in each state, a high degree of international cooperation is required to eradicate the danger which the subversive activities of international communism pose for the American States; and
The aggressive character of the international communist movement continues to constitute, in the context of world affairs, a special and immediate threat to the national institutions and the peace and security of the American States, and to the right of each state to develop its cultural, political, and economic life freely and naturally without intervention in its internal or external affairs by other States,
The Tenth Inter-American Conference
Condemns:
The activities of the international communist movement as constituting intervention in American aiffairs;
Expresses:
The determination of the American States to take the necessary measures to protect their political independence against the intervention of international communism, acting in the interests of an alien despotism;
Reiterates:
The faith of the peoples of America in the effective exercise of representative democracy as the best means to promote their social and poetical progress; and
Declares:
That the domination or control of the political institutions of any American State by the international communist movement extending to this Hemisphere the political system of an extra continental power, would constitute a threat to the sovereignty and political independence of the American States, endangering the peace of America, and would call for a meeting of consultation to consider the adoption of appropriate action In accordance with existing treaties.
https://www.jus.uio.no/ior/personer/vit/olefa/00 working-folder/ole_kristian/uaktuelle/declaration_solidarity.xml
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Once again: declaring that the adoption of a Marxist-Leninist government by any Latin American nation was ipso facto proof of domination by an extra-continental power was US and OAS policy in the Cold War in OTL. I just don't see how your POD changes anything in this respect. (Also, in 1951 the Fourth Meeting of Consultation of Ministers of Foreign Affairs of American States: "The expansionist activities of international communism require the immediate adoption of measures to safeguard the peace and the security of the Continent..."
https://archive.org/details/departmentofstatx2451unit/page/606)