I listened to episode 23 of the Empire podcast "The Fall of Constantinople" last night. (More accurately I listened to it at about 10:30 in the evening when Virgin Media came back online.)
At the end William Dalrymple says something along the lines of:
Russia now sees itself as the last surviving pillar of Orthodoxy. Rome was the first Rome, Constantinople was the second Rome, Moscow now regards itself as the third Rome. They see themselves as the last true Christians.
Interesting stuff; for all that I've referred before (Icons passim) to an sort of unholy trinity, comprising Putin, Aleksandr Dugin and Patriarch Kirill, marrying Russian irredentism and a Slavic manifest destiny; I may have played down the religious angle.
Deep history can be surprisingly relevant to contemporary events and tensions. There are now two Orthodox churches in Ukraine. The older and larger church is the Ukrainian Orthodox Church – Moscow Patriarchate; a branch of the Russian Orthodox Church, it is under the spiritual authority of Patriarch Kirill (see paragraph above) of Moscow.
By contrast, the second, newer church, the Orthodox Church of Ukraine, celebrates its independence from Moscow. With the blessing of the Ecumenical Patriarch Bartholomew of Constantinople, a solemn council met in Kyiv as recently as December 2018, created the new church, and elected its leader, Metropolitan Epifaniy. In January 2019, Patriarch Bartholomew formally recognized the Orthodox Church of Ukraine as a separate, independent and equal member of the worldwide communion of Orthodox churches.
I've still got a lot of work to do understanding all this.