Vatican II is an Ecumenical Council pt. II
Paul VI, who inherited the Council stated the following:
“The Second Vatican Ecumenical Council, assembled in the Holy Spirit and under the protection of the Blessed Virgin Mary, whom we have declared Mother of the Church, and of St. Joseph, her glorious spouse, and of the Apostles SS. Peter and Paul, must be numbered without doubt among the greatest events of the Church. In fact it was the largest in the number of Fathers who came to the seat of Peter from every part of the world, even from those places where the hierarchy has been very recently established. It was the richest because of the questions which for four sessions have been discussed carefully and profoundly. And last of all it was the most opportune, because, bearing in mind the necessities of the present day, above all it sought to meet the pastoral needs and, nourishing the flame of charity, it has made a great effort to reach not only the Christians still separated from communion with the Holy See, but also the whole human family.
At last all which regards the holy ecumenical council has, with the help of God, been accomplished and all the constitutions, decrees, declarations and votes have been approved by the deliberation of the synod and promulgated by us. Therefore we decided to close for all intents and purposes, with our apostolic authority, this same ecumenical council called by our predecessor, Pope John XXIII, which opened October 11, 1962, and which was continued by us after his death.”
Please note that both Popes state this council is Ecumenical.