Russia’s military offensive in Ukraine effectively means two Orthodox Christian countries are at war with each other.
So how much have religious tensions between Russia and Ukraine contributed to the conflict?
The Russian Orthodox Church is rarely seen to question the action of the Russian regime and in 2019, the spiritual leader of the Eastern Orthodox Churches, Ecumenical Patriarch Bartholomew recognised the efforts of Ukrainians who wanted their own national identity free from religious authority.
The Orthodox Church of Ukraine was created, severing its links with the Russian Orthodox Church.
Some academics believe the split in the Orthodox church has contributed to the present situation, with President Putin accusing Ukraine’s government of repressing the Ukrainian Orthodox Church – which is attached to the Patriachate of Moscow.
He said Ukrainian authorities have cynically turned the split in the Church into an instrument of state policy.
Martyn Whittock is a Christian historian and author and he's been giving his view to Premier: “I’m shocked, but I'm not entirely surprised.
"I suggested that Putin might do something like this once the Winter Olympics was over.
"It also coincides with the anniversary of the Maidan, which was basically Ukraine, overthrowing its pro-Russian President back in 2014.
“I have no evidence that he (Putin) had an arrangement with China, but it would not be impossible that there have been behind the scenes discussions.
"But this week is the anniversary of that 2014 date, which has triggered a lot of Russian involvement in Ukraine, the seizure of Crimea, and then the support of the breakaway republics of Luhansk and Donetsk, in the Donbass.
"So that may be a more important anniversary, as far as Putin is concerned.
"Payback time if you like.
“The Russian Orthodox Church has stood to a very large extent behind Putin.
"It’s supportive of Putin and Putin regards it as one of the key aspects of Russian national identity, although, of course, there are many other minorities in Russia.
"But he has clearly regarded Russia as being this Orthodox nationalist identity.
"The split in the Orthodox Church went down very, very badly indeed, because it was one more aspect of Ukraine declaring itself to be independent of Moscow.
“We now have two orthodox nations, Ukraine and Russia, who are now at war with each other.
"When Ukraine voted to leave the Soviet bloc when it broke apart in 1991, that went down very badly with Russian nationalists.
"They've always wanted Ukraine back.
"The problem is, the more pressure they put on Ukraine, the more Ukrainian support for things like joining the EU or joining NATO increases, which then increases Russian anxiety.
"It is a very, very dangerous circular loop of distrust that the Russians have triggered here.
“We know very little about Putin personally but one suspects he wasn’t promoted for his spirituality.
"Certainly he taps into orthodoxy and he makes statements about his faith.
"But I don't know where Putin stands with God.
“It's a very grave moment in history.
"Blessed are the peacemakers and at the moment, peacemakers and people who are promoting peace and understanding and reconciliation are really crucially needed in this situation.
"It’s also important to stand up boldly against aggression as well and it's keeping those two things in tension and balanced, which really is the profound challenge for Christians and indeed for the West at the moment.”
Ukraine was for centuries known as ‘Malorossiya’ or ‘Little Russia.
The country voted for independence in 1991.
In 2014, over 100 people were killed during mass protests that ousted the country's Russia-friendly president, Viktor Yanukovych.
The people, known as 'The Heavenly Hundred' are commemorated each year on February 20, to mark the day when riot police opened fire on protesters.
After the fall of the Yanukovych government, Russia annexed Crimea and supported rebels in Ukraine's east in a conflict that has killed over 14,000 people since 2014.