MOSCOW (AP) — As Russian troops wage a ferocious house-to-house fight for control of strongholds in eastern Ukraine, a parallel battle is unfolding in the top echelons of military power in Moscow, with President Vladimir Putin reshuffling his top generals while rival camps try to win his favor.

The fighting for the salt mining town of Soledar and the nearby city of Bakhmut has highlighted a bitter rift between the Russian Defense Ministry leadership and Yevgeny Prigozhin, a rogue millionaire whose private military force known as the Wagner Group has played an increasingly visible role in Ukraine.

Putin’s shakeup of the military brass this week was seen as a bid to show that the Defense Ministry still has his support and is in charge as the troubled conflict nears the 11-month mark.

Prigozhin rushed Wednesday to declare that his mercenary force had captured Soledar, a claim rejected by Ukrainian officials. Furthermore, his statement that the prize was won exclusively by Wagner challenged the accounts from the Defense Ministry, which described action by airborne troops and other forces in the battle for Soledar.

The 61-year-old Prigozhin, who was known as “Putin’s chef” for his lucrative catering contracts and was indicted in the U.S. for meddling in the 2016 presidential election, has expanded his assets to include Wagner, as well as mining and other spheres. He has scathingly criticized the military brass for blunders in Ukraine, saying Wagner was more efficient than regular troops.

He has found a powerful ally in Chechnya’s leader Ramzan Kadyrov, who has deployed elite troops from his southern Russian region to fight in Ukraine and also assailed the military leadership and the Kremlin for being too soft and indecisive.

While both have pledged loyalty to Putin, their public attacks on his top generals openly challenged the Kremlin’s monopoly on such criticism, something that Russia’s tightly controlled political system hadn’t seen before.

In the reshuffle announced Wednesday, the Defense Ministry said the head of the General Staff, Gen. Valery Gerasimov, was named the new chief of Russian forces in Ukraine, while the former top commander there, Gen. Sergei Surovikin, was demoted to Gerasimov’s deputy after only three months on the job.

The Washington-based Institute of the Study of War saw the reshuffle as an attempt by the Kremlin to “reassert the primacy of the Russian Ministry of Defense in an internal Russian power struggle,” weaken the influence of its foes, and send a signal to Prigozhin and others to reduce their criticism.

Prigozhin and Kadyrov have repeatedly criticized Gerasimov, the main architect of the Russian operation in Ukraine, and held him responsible for military defeats while praising Surovikin.

Russian troops were forced to retreat from Kyiv after a botched attempt to capture the Ukrainian capital in the opening weeks of the war. In the fall, they hastily pulled back from the northeastern Kharkiv region and the southern city of Kherson under the brunt of a swift Ukrainian counteroffensive.

Surovikin directed the retreat from Kherson, the only regional center captured by Russia, and was credited for shoring up command and increasing discipline in the ranks. But a Ukrainian missile strike on Jan. 1 in the eastern town of Makiivka killed scores of Russian troops and tainted his image.

Political analyst Tatiana Stanovaya observed that Gerasimov’s appointment marked yet another attempt by Putin to resolve his military problems by shaking up the brass.

“He is trying to reshuffle the pieces and is therefore giving chances to those who he finds persuasive,” she wrote. “But in reality, the problem is not with the people, but with the tasks at hand.”

Stanovaya argued that Gerasimov could have asked for “carte blanche in the heat of verbal battles against the background of some very tense discussions.” For Putin, ”This is maneuvering, a tug-of-war between Surovikin (and sympathizers like Prigozhin) and Gerasimov,” she added.

Gerasimov, who began his military career as a Soviet army tank officer in the 1970s, has been chief of the General Staff since 2012 and was seen at the start of the conflict in February sitting next to Defense Minister Sergei Shoigu at a very long table with Putin. His appointment to directly lead the forces in Ukraine drew stinging comments from some Russian hawks.

Viktor Alksnis, a retired Soviet air force colonel who spearheaded botched attempts to preserve the USSR in 1991, noted that Gerasimov had overseen the action in Ukraine even before his appointment.

“This decision reflects the understanding by our political and military leadership that the special military operation has failed and none of its goals has been fulfilled in nearly a year of fighting,” Alksnis wrote on his messaging app channel. “Replacing Surovikin with Gerasimov will change nothing.”

Mark Galeotti, who specializes in Russian military and security affairs at University College, London, said the appointment handed Gerasimov “the most poisoned of chalices” as he now will bear direct responsibility for any more setbacks.

“Gerasimov is hanging by a thread,” Galeotti said in a commentary on Twitter. “He needs some kind of win, or a career ends in ignominy. This may well suggest some kinds of escalation.”

Galeotti also warned that frequent reshuffling of Russia’s generals could erode allegiance in the officer corps.

“If you keep appointing, rotating, burning your (relative) stars, setting unrealistic expectations, arbitrarily demoting them, that’s not going to win loyalty,” he said.

Prigozhin, meanwhile, has taken advantage of military setbacks in Ukraine to expand his clout by making the Wagner Group a pivotal element of the Russian fighting force, augmenting the regular army that has suffered heavy attrition.

Ukrainian officials alleged Wagner contractors were suffering massive losses in the fighting in Soledar and Bakhmut, advancing “on the bodies of their own comrades.”

Once convicted of assault and robbery, for which he served time in prison, Prigozhin in recent months went on a tour of Russia’s sprawling network of penal colonies to recruit inmates to join Wagner’s forces to fight in Ukraine in exchange for pardons.

He recently released a video showing about 20 convicts allowed to leave the ranks of fighters after a half-year on the front line, while also making clear that anyone breaking ranks will face brutal punishment.

Footage posted in the fall showed a Wagner contractor being beaten to death with a sledgehammer after allegedly defecting to the Ukrainian side. Despite public outrage and demands to investigate the incident, authorities have turned a blind eye to it.

Observers have warned that by giving Prigozhin a free hand to run Wagner as a private army governed by medieval-style rules, the government has effectively planted dangerous seeds of possible upheaval.

“In the end, there is chaos and the expansion of violence -– extrajudicial and illegal,” predicted Andrei Kolesnikov, an analyst with the Carnegie Endowment.