Giacomo Galeazzi reviews for La Stampa the new biography of Paul VI written by Andrea Tornielli, and mentions that what many considered a conspiracy theory was true: there was indeed a secret agreement, led by Cardinal Tisserant, between the Soviet Union and the Holy See (under John XXIII) in 1962 - an agreement which Paul VI also respected. As Galeazzi says:
In a note of November 15, 1965, in fact, Montini explicitly mentions among "the commitments of the Council" also that of "not mentioning Communism (1962)". The indication of the date at the end of the sentence written by Paul VI refers to the secret agreement, related by Tisserant, between Rome and Moscow.
And this would explain why the Second Vatican Council, which dealt with all sorts of issues, relevant and irrelevant alike, ignored the most challenging menace of its time: Communism.
