Since the Russian invasion of Ukraine, the Vatican has repeatedly reiterated that Pope Francis would be willing to mediate if both sides so wished.
However, so far it does not look as if the Vatican could play a leading role on a diplomatic level.
On Friday the Pope took a global spiritual initiative to help end the war.
In doing so, he made use of Marian piety.
Matthias Rub
Political correspondent for Italy, the Vatican, Albania and Malta based in Rome.
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In St. Peter's Basilica, Francis consecrated "all humanity, especially Russia and Ukraine, to the Immaculate Heart of Mary" with a prayer.
The accompanying supplication to Mary, the Mother of God, which the Vatican published in 35 languages, says: “The people of Ukraine and Russia, who lovingly worship you, come to you, and your heart beats for them and for all peoples who suffer from war, hunger, injustice and poverty.” The Pope also prayed: “Give the end of war and give peace to the world.” In many countries dioceses joined this act of consecration.
In Germany, for example, the archbishops of Cologne and Paderborn, Rainer Maria Cardinal Woelki and Hans-Josef Becker.
The 94-year-old Pope Emeritus Benedict XVI.
had announced his participation in the act of consecration.
What Maria says about Russia
Critics have argued that this act of consecration blurs the line between aggressor and victim, a reproach the Pope also faces in his appeals for peace in Ukraine.
Neither he nor the Vatican's second man and chief diplomat, Cardinal Secretary of State Pietro Parolin, have so far explicitly branded Russia and President Vladimir Putin.
However, the Vatican's rhetoric in condemning Russia's war in Ukraine and the slaughter of innocent lives and destruction of civilian targets has become increasingly explicit over the course of the four weeks of war.
The ritual of the act of consecration goes back to the reports of three shepherd children about Marian apparitions in Fátima, Portugal, which are said to have taken place in 1917.
They stated that the Blessed Mother Mary had appeared to them in radiant white and surrounded by heavenly shimmers.
Today the barren field of Cova da Iria near Fátima, where the apparition is said to have taken place, is one of the world's most important Marian pilgrimage sites.
Six to eight million pilgrims are counted every year.
Nine million believers came to the centenary of the Marian apparitions in 2017.
Pope Francis was among them on May 13, 2017.
Francis had ordered the Polish Curia Cardinal Konrad Krajeswki, head of the alms administration in the Vatican, to Fátima on Friday for the synchronous dedication ceremony.
Our Lady is said to have revealed three prophetic secrets to the children of Fátima.
In the second Fátima secret of 1917, which the children, according to their own statements, were not allowed to announce until 1942 at the behest of the Virgin, Russia is expressly mentioned - no other country is mentioned in the mysteries of Fátima.
In order to prevent God from punishing people “for their misdeeds through war, famine and persecutions”, Russia must be consecrated “to my Immaculate Heart”, according to the testimony of the children of Fátima, the Virgin demanded during her apparitions: “If one hear my wishes, Russia will be converted and there will be peace.
If not, it will spread its heresies across the world, provoking wars and persecution of the Church.”
The second Fátima Secret of 1917 is set against the historical background of the Tsar's resignation during the February Revolution of 1917. It is interpreted as a prophecy of the seizure of power by Lenin's (godless) Bolsheviks and thus of Russia's defection from the Christian faith.
In the Ukraine and in Poland it is the hope of Catholics, but also of some Orthodox Christians, that Mary will stop the invaders and help stop the Russian advance.
Orthodox Christians in Russia may be hoping that the Pope's act of consecration will strengthen Russia in its fight to defend true Christianity against the West, which has fallen away from the true faith.