Since Friday night, Yevgeny Prigozhin and his mercenary Wagner group have plunged Russia and its military leadership into an ill-timed seismic dispute that has taken the country in the direction of civil war.
In an explosive message published on Friday, Prigozhin spat fury at Russia’s top brass and took his troops into the Russian city of Rostov-on-Don, occupying a key military base in the city.
Amid a highly dynamic and rapidly changing situation, here are all your key questions answered.
Who is the Wagner Group?
The Wagner Group was first formed in 2014 by a band of irregular forces serving in the Donbas region of Ukraine, when Russia first launched offensives to the east of the country.
Its leader, Prigozhin, began as a catering magnate who has been closely linked to President Vladimir Putin throughout his two decades in power.
Prigozhin began to transform himself into an international warlord through his involvement in supporting Russian-backed separatists in the Donbas.
The Wagner Group soon bloomed into a key arm of realising Russia’s interests abroad; close enough to the Kremlin to be reliable, at arm’s length enough to be deniable.
In the decade since they were first formed, Wagner contractors had served in numerous countries across the Middle East and North Africa - most notably Libya, Sudan and Syria.
Wagner is, however, just one of 10 private Russian military enterprises now operating in Ukraine - one of which belongs directly to the minister of defence himself.
How did the rebellion begin?
The Wagner Group has been a key part of Russia’s invasion of Ukraine, handing Russia one of the few major territorial gains since the war began, in the capture of Bakhmut.
Relying heavily on convict recruits from Russian jails, Wagner forces sustained heavy losses that were blamed on Defence Minister Sergei Shoigu and Vasily Gerasimov, the head of the Russian Armed Forces.
An increasingly prominent feature on the frontlines of Russia’s brutal invasion, Prigozhin himself began taking brazen potshots at the military leadership, accusing them of failing to supply troops with essential ammunition and equipment to prosecute the war effectively.
The relationship between Russia’s military command and the mercenary leader became increasingly bitter - and publicly so - after Prigozhin unleashed a torrent of swearwords aimed at Shoigu and Gerasimov in a video surrounded by dozens of dead Wagner Group recruits.
The Wagner chief said his forces were dying as Russia’s military leaders "sit like fat cats" and do nothing.
The situation came to a head on Saturday after Prigozhin claimed the Russian military had struck a Wagner base, seeking to kill him.
The head of the Wagner mercenary group announced early on Saturday that he had crossed into Russia and seized control of a key military headquarters, vowing to topple Moscow's military leadership and saying he and his 25,000 fighters were "ready to die".
What does Prigozhin want?
Prigozhin has said that his actions are “not a military coup but a march for justice”.
Anyone familiar with the Wagner Group’s ruthlessly brutal tactics across the Middle East and North Africa may, however, question his commitment to "justice".
Neither should his actions be taken to show an ideological distaste for the war in Ukraine. Prigozhin has called the invasion “a sacred war against those who offend Russian people" in a recent statement.
But his battle-hardened forces have, by his account, tired of the current leadership who have been unable to deliver effective gains on the ground.
“Learn to hear and listen to your people. Otherwise, they will simply stop hearing and listening to you. Fear the wrath of a patient man. But more than that, fear the wrath of a patient people,” said the Wagner-leaning Telegram group the Grayzone on Saturday.
How has Putin responded?
Angrily. He has likened Prigozhin’s actions to the Russian Revolution in 1917 which deposed Tsar Nicholas II.
“This was the same kind of blow that Russia felt in 1917, when the country entered World War I, but had victory stolen from it,” said Putin in his tense address to the nation on Saturday as Prigozhin's troops appear to be making their way to Moscow.
“Anti-terrorist” measures to strengthen security are now being seen on the streets of Moscow as a result of “incoming information”, according to the mayor Sergei Sobyanin.
It is clear that Putin, while blindsided by the day's events, is not in the mood to negotiate with Prigozhin.
Is there a way back into the fold for Prigozhin?
The Wagner chief has been careful to avoid directly criticising the president, mostly taking aim at Shoigu and Gerasimov for mishandling the Russian invasion of Ukraine.
His line appears to be a reckoning, over regime change - for now - but he may feel his options for compromise are severely limited as the rhetoric escalates.
However, he may have reached the point of no return on Saturday after Putin called him a traitor during his TV address, for leading what he called an ‘armed mutiny’ and promised swift retribution.
After calling Prigozhin’s actions a “knife in the back of our people”, it is not clear how Prigozhin might remove such a knife in the eyes of the Russian president.
Does this mean civil war in Russia?
Most observers have been careful to describe Saturday’s events as anything but a mutiny or rebellion, but some have acknowledged that the situation could easily escalate.
Much of Russia’s elites - including the military establishment - rely on Putin for their continued existence within the Russian state. Most analysts believe that, while defections within the military to Prigozhin are possible, it’s more likely that key players will rally to Putin’s side.
As a major nuclear power, civil strife in Russia could have a highly destabilising effect on world security.
What does this mean for the war in Ukraine?
Ukraine said on Saturday that unrest in Russia presents an opportunity for Kyiv, weeks after announcing a gruelling, inch-by-inch counter-offensive against Russian positions.
"What does this mean for us? It is a window of opportunity," said Deputy Defence Minister Ganna Malya on Saturday.
President Zelensky chimed in that "Russia's weakness is obvious" and that the longer Moscow keeps its troops and mercenaries in Ukraine, the more chaos it would invite back home.
Some analysts believe that now might be the perfect time to launch a major counter-attack across the eastern front in Ukraine.
Others say that a major change on the frontlines in Ukraine could, in short order, reunite the Russian factions. Better, some believe, to let the fissure in the Russian military machine grow into a widening crack.