Following the Ukraine government's most recent retaliatory escalation, which saw the death of some 50 people in Odessa on Friday, everyone has been waiting to see how the Kremlin would respond. For now while Putin appears to be merely biding his time until the various referendum votes take place in east Ukraine, quite confident they will have the same outcome as the Crimean vote to join Russia, thus giving him a legitimate basis to annex further Ukraine regions, some "independent" military units, according to local press, appear to be making their way into Ukraine: Cossacks, that roving group of militants (and sometimes mercenaries) who have been so instrumental in shaping the history of both Ukraine and Russia [3].
Several clips distributed earlier on social networks purport to show Russian Cossacks who have entered eastern Ukraine, specifically the town of Anthracite.
While one can't determine the validity of these reports (at least not yet), it is certain that both the Ukraine government and NATO will latch on to reports that Russian mercenaries are operating and supporting the eastern militias. However, what this will achieve aside from even more futile diplomatic bluster, is unclear.
And for those who are not familiar with the Cossack culture, here is a reminder from SkyNews [4]:
Russian Cossack leaders have plans to cross into Ukraine to "rescue" Russian-speaking communities in the east of the country, after providing militias which helped Vladimir Putin's Crimean land grab.
Atamans, or headmen, of two Cossack communities, said they had traditional claims on the lands on both sides of the border, adding: "One day we will take them back."
But they warned they would expect rewards for acting as the Russian president's muscle.
Romanticised by the Tsars but crushed by the communists, Russia's Cossack communities are rapidly rebuilding themselves and have become a powerful symbol of nationalist fervour.
To many Russians, they have betrayed their martial roots to become henchmen for the worst aspects of Mr Putin's rule.
Most recently, they have been seen on the streets of Crimea, often heavily armed and sometimes drunk, blockading Ukrainian troops in their barracks and running road blocks.
They were also filmed whipping members of the band Pussy Riot when the all-female group attempted a street performance at the Winter Olympics in Sochi.
They also admit being close to other hard-line Slav nationalists, Serbs in particular.
Earlier this month, Alexei Sushkov was responsible for hosting a group of black-bearded Chetniks, Serb militia, in Sevastopol.
They serve under a death's head insignia and volunteered to help with Russia's invasion of Crimea.
"You have to have great personal discipline. You need to be religious and of good character to be a Cossack," he confided.
Mr Sushkov is not so much a bear of a man as a man who looks like he ate a bear, and the meal was a little wanting.
He says that when the Cossacks invaded Crimea, they brought their own weapons or picked them up from local authorities when they arrived. They also turned up with an armoured personnel carrier - or a "mini-tank", as they called it.
He spoke with passion about how he wished he had been able to help the Serbs fight in the former Yugoslavia and of how they were bilked of the province of Kosovo, which won its independence after a civil war with Serbia and Nato bombardment of Serb forces.
"Russia was weak back then," he growled.
On the outskirts of Taganrog, a few miles from the border with Ukraine, Cossacks demonstrated how they were reviving the tradition of horsemanship which was central to the Cossacks' culture.
Their warlike tendencies and citizen cavalry meant their regiments became a celebrated part of Tsarist imperial life.
The Don Cossacks ruled a vast Host on both sides of the River Don for centuries and were given a degree of autonomy from central government.
When many sided with the White Russians against the Bolsheviks in the early part of the last century, though, they were crushed by the Soviet rulers who snuffed out any potential threats to the Party's hegemony.
They are gentle with their horses, ride with light hands and are freely affectionate towards their mounts - kissing and cuddling them like beloved children.
Such tenderness is in sharp contrast to what they have planned, the details of which they won't share, in the neighbouring Ukrainian region of Donetsk.
"We are ready to go in whenever the time comes to protect our people," said Andrei Lovlenski, the ataman of the Taganrog Cossacks. "We are ready."
In Rostov-on-Don, a city of one million people and home to a vast helicopter factory, the Cossack revival is being driven by Timor Okkert, the local ataman.
He is a combat veteran of Russian conflicts in Georgia, Chechnya and Nagorno-Karabakh.
Close to the Patriots' Sports Club where his Cossack disciples work out and learn martial arts, his offices house an impressive collection of swords and automatic weapons.
He led Cossacks into Crimea and is convinced he will be asked to go into other parts of Ukraine too.
"We've been used like this for many centuries," he said.
But what does he expect from Mr Putin in return?
Mr Okkert allows a brief sneer to cross his face.
"That's a rhetorical question," he said. "We're still waiting for an adequate answer from our government."
That's a warning - it means once unleashed, the Cossacks may be hard to control.