Moscow's Russian Orthodox Patriarch Kirill congratulated Pope Francis on Monday as the pontiff marks his tenth anniversary in the role, sparking hope of a thaw in relations.
In his text, Kirill also mentioned dialogue between the religions, comments that were welcomed by the Vatican, as there has been no communication between the pope and the patriarch in months.
Pope Francis has expressed the hope several times that he could talk with Kirill about ways to bring peace to Ukraine, which is battling a full-scale Russian invasion.
However, Kirill is a firm supporter of the Russian war on Ukraine and the pope has recognized that such a dialogue is unlikely to lead to success.
It was not initially clear whether the patriarch's letter might be a sign that relations are easing.
According to an official statement issued by the Russian Orthodox Church, Kirill expressed the hope that "in the difficult times we are experiencing, dialogue between religious leaders can bear good fruit." He also sent wishes for the pope's health and peace of mind.
Monday marks the tenth anniversary of Francis' election as pope and he received numerous congratulations from senior members of the clergy and politicians.
In a podcast on Vatican News, the pope said that at the moment, what hurts and worries him most are the wars in the world. When asked what he wished for, he replied: "Peace, we need peace."
