No, like most internal turmoil in Latin America, it was purely a domestic issue following the removal of a five-time president who had three previous times failed to complete his term of office.
With a few exceptions, the intervention of the US in Latin American politics has been quite limited.
"Fairness" dictated to a great extent how far the electronic media would go, since they knew that every action might have an equal opposite reaction. That's why the few stations that editorialized back then talked about sewer bond issues and not the Viet Nam War.
I'm really quite tired of the "pill popper" label that a few people put on Limbaugh. He had a problem, rather briefly, and he handled it. In an era where a large percentage of the population wants reduced sanctions on victimless crimes like possession, your attitude is reactionary.
And the fact remains that for at least his first two decades, the show was very entertaining and popular.
The Fairness Doctrine was not "voluntary".
Actually, it was pointed out that the diversity of media thus far in the Internet era accompanied by more radio and TV stations and a profusion of cable channels made such a rule obstructive.