Ukrainian separatists have confirmed that Igor Girkin, better known as Strelkov, has stepped down from his position as a military chief, making him the third rebel leader to quit within a week.
Strelkov relinquished his position as the defense minister of the self-proclaimed People's Republic of Donetsk on Thursday, insurgency mouthpiece Novorosinform.org reported.
The site said Strelkov has a new job, but did not elaborate. It reported on Wednesday that the rebel leader was heavily injured in fighting, but his representatives later denied it.
Warlord Vladimir "Tsar" Kononov has been appointed Strelkov's acting replacement, the Interfax news agency reported, citing Sergei Kavtaradze, a member of the insurgents' security council.
Russian national Strelkov becomes the third rebel leader to quit within the space of week.
The heads of the two self-proclaimed republics, Alexander Borodai of Donetsk and Valery Bolotov of the People's Republic of Luhansk, have also submitted their resignations.
Bolotov, a Ukrainian citizen, quit his position on Thursday, citing an injury. Borodai, a Russian political consultant, resigned last Thursday saying he accomplished his mission of turning the insurgency into a "real state."
All three have led the rebellion in Ukraine's east, where separatists have been calling for the region to join Russia since spring. However, in recent weeks the rebellion has been ground down by Ukrainian government's forces, and the insurgency is now isolated to the cities of Donetsk and Luhansk.
A number of Western countries have accused the Kremlin of supplying separatists in Ukraine with arms, leading them to impose sanctions against the Russian economy. Moscow denies the charges and retaliated in early August with a sweeping ban on food imports from the West.
Russian President Vladimir Putin on Thursday delivered a surprisingly dove-ish speech in Crimea, a Ukrainian region annexed by Russia in March.
The speech prompted analysts to say that Russia is finally looking for a way to back out of the Ukrainian standoff, and could have pushed rebel leaders into resigning as part of the plan.
Strelkov, a 43-year-old retired FSB colonel, is a veteran of the Bosnian war and the Transdnestr conflict who also worked as a war correspondent in Chechnya. He is also known for his fondness of historical reenactment, with a particular focus on World War I and the anti-Bolshevik struggle of the Russian Civil War.