Since the start of the crisis politicians and media in the two ex-Soviet states have raised the ghosts of over half a century ago, accusing their opponents of "fascist" tendencies and painting them as the 21st century successors of Adolf Hitler and Nazi Germany.
Such moves play on a mutual suspicion in both countries that has lingered since World War II.Many Ukrainians see Russia as an expansionist power, while Moscow has accused the protesters who ousted president Viktor Yanukovych of being dangerous right-wing extremists.
News bulletins on Russian state television make almost obsessive reference to the "fascists and Banderovtsy" who Moscow claims are now running Ukraine.
Banderovtsy ?- a word barely used in Russia before the crisis but which has now gone viral -- is a reference to the followers of Stepan Bandera, the anti-Soviet wartime leader of the Ukrainian Insurgent Army (UPA) who was assassinated by a Soviet agent in Munich in 1959.
Few groups from World War II have as divisive a legacy as the UPA. It is reviled in Russia, while its members are lauded as heroic leaders of the independence struggle in western Ukraine.
The UPA battled the Red Army and carried out massacres of Poles. They fought but also collaborated with occupying Nazi forces and some members joined a special division of the SS.
- Russia raises Bandera's ghost -
President Vladimir Putin said he was alarmed by the resurgence of Bandera's ideas in Ukraine in his historic address in the Kremlin on March 18 as Russia seized Crimea.
"It has already become clear to everyone what the Ukrainian inheritors of Bandera ?- the stooge of Hitler in World War II ?- want to do," he said.
Putin justified Russia's taking of Crimea ?- condemned as a "land grab" in the West ?- as protecting the Russian-speaking locals from "fascist" Ukrainian nationalists.
But by bringing up Bandera and the UPA so often, Russia may only be bolstering their standing in Ukraine's collective memory.
"The Russian authorities did so much to identify the Ukrainian revolutionaries with wartime Ukrainian nationalists that this actually increased the level of acceptance of nationalist slogans and heroes," said Serhy Yekelchyk of the University of Victoria in British Colombia.
"The more Putin meddles in Ukraine, the higher such acceptance will be."
Even before the crisis, Ukrainian nationalists could draw on a long list of historical grievances against Russia.
Some Ukrainians even accuse their powerful neighbour of stealing the word "Rus" -- the name of the original Slavic state founded around Kiev -- relegating the country to a name that loosely means "borderland".
Moreover, many in Ukraine will never forgive Russia's failure to atone for the millions who died in the 1930s Holodomor mass famine, which has been blamed on Stalin's forced collectivisation of agriculture.
- Playing the 'Putin-Hitler' card -
But the Nazi parallel has also been made by politicians and senior media commentators in Ukraine, a particular slight to Russia whose greatest pride is the victory over Nazi Germany.
Broadcaster Savik Shuster, whose Shuster Live show on Ukraine's First Channel is the country's most influential political show, has repeatedly compared Putin to Hitler in recent weeks.
In the weekend edition of his programme, he compared Putin's March 18 address to the speech made by Hitler to the Reichstag parliament in 1939 at the start of World War II.
"I suggest you look at Vladimir Putin?s speech and see how much it has in common with the speech by Adolf Hitler to the Reichstag," said the Lithuanian-born journalist.
Former Ukraine prime minister Yulia Tymoshenko, who took part in the studio discussion, nodded vigorously in agreement.
But Russian lawmakers who passed the legislation incorporating Crimea into Russia claimed to be simply continuing the USSR's anti-fascist struggle.
They pinned to their lapels the St George's ribbon, which in recent years has become the main symbol for remembering the war.
One of the country's top universities, the Moscow State Institute of International Affairs (MGIMO), this week sacked a professor who compared Moscow's takeover of Crimea to the Nazi annexation of Austria.
"In the Russian official discourse, the struggle for the rights of Russian speakers became a symbolic continuation of the Great Patriotic War," said Yekelchyk.