We had, after all, no other recourse to protect ourselves, no other document, let`s say, than the Monroe Doctrine. So that could be cited as a cause for intervention if and when it might become necessary.
So you`re quite right that when... as the Cold War grew and expanded out of Europe, we ourselves had to take refuge behind the shield of the Monroe Doctrine.
So the reason that the Bay of Pigs failed was that the original promise made by Eisenhower was not kept by the subsequent Administration. It allowed hostile air to wipe out the approaching invasion force.