Russia has replaced the general in charge of its trouble-plagued war against Ukraine, amid signs of dissension among President Vladimir V. Putin’s top allies — a shake-up that critics said would not address what ails the Russian military.
Gen. Valery V. Gerasimov, whose appointment the Defense Ministry announced on Wednesday, is a longtime Kremlin ally, chief of the military general staff since 2012, and an executor of the failed plan for the initial invasion in February. It was the second time in just three months that the ministry replaced the chief of the war effort.
Outside analysts and hawkish Russian war bloggers said the change was a far cry from the radical overhaul the Russian armed forces need to become more effective.
“The sum does not change, just by changing the places of its parts,” wrote one prominent blogger who goes by the name Rybar.
The reshuffling of commanders came as the Kremlin sharply contradicted a key Putin ally about the pitched combat for Soledar, a small town in eastern Ukraine.
On Tuesday, Yevgeny V. Prigozhin, head of the Wagner mercenary force, said that his troops had seized control of Soledar, posted online a photo of himself with some of the soldiers in what he said was the town’s famous salt mine, and made a point of claiming that only Wagner fighters had been battling there on behalf of Russia.
But both the Russian Defense Ministry and Ukrainian commanders contradicted those claims on Wednesday, saying that combat continued in Soledar and that the town had not yet fallen. The Russian ministry also said its own troops were fighting there.
Dmitri S. Peskov, the Kremlin spokesman, urged journalists to wait for official announcements about whether the city had been captured, adding that “tactical successes are certainly very important as they come at a rather expensive price.”
Neither he nor the ministry mentioned Wagner or its head by name, but their statements amounted to a rebuke of Mr. Prigozhin, who on Wednesday reiterated his claim that his forces had taken control of Soledar.
Starting with the failed attempt to seize Kyiv in a lightning assault in February and March, the Russian war effort has been marked by missteps, reversals and heavy casualties.
It shifted to a slow, grinding offensive concentrating on the eastern Donbas that succeeded in capturing several cities at high cost, but then stalled. Then in late summer came a swift Ukrainian counteroffensive that reclaimed a significant amount of occupied territory, and forced a chaotic Russian retreat from the northeastern Kharkiv region.
That prompted the appointment in October of a new Russian commander for the war in Ukraine, Gen. Sergei Surovikin, who had previously headed Russian forces in Syria, where he gained a reputation as a ruthless but effective commander.
General Surovikin revamped a disjointed military structure in Ukraine and ordered construction of defensive lines to slow Ukrainian advances. He also advocated and organized the orderly retreat from the southern city of Kherson and surrounding areas west of the Dnipro River, a move that military analysts said was necessary but that Mr. Putin was said to have previously forbidden.
Now General Surovikin has effectively been demoted, becoming one of three deputies to General Gerasimov. Analysts said the change showed that Mr. Putin remains focused on projecting stability and maintaining the power balance among key allies, rather than correcting the military’s fundamental flaws.
“They have taken someone who is competent and replaced him with someone who is incompetent, but who has been there a long time and who has shown that he is loyal,” said Dara Massicot, senior policy researcher at the RAND Corporation in Washington. “Whatever is happening in Moscow, it is out of touch with what is happening on the ground in Ukraine.”
In an intelligence assessment, the British Defense Ministry said the switch was “a clear acknowledgment that the campaign is falling short of Russia’s strategic goals.” But it said the move would meet with “extreme displeasure” among pro-war ultranationalists “who have increasingly blamed Gerasimov for the poor execution of the war.”
Russian setbacks slowed under General Surovikin, but did not stop. Ukrainian forces, armed with increasingly sophisticated Western weapons, made more gains in Kherson Province and in the Donbas region in the east, and repeatedly struck targets far behind the front lines. A monthslong Russian drive to capture the small city of Bakhmut, in the Donbas, has cost many lives but gained little ground.
A concerted effort destroy Ukraine’s energy systems has failed to bombard the country into submission, while leaving Russia short of precision munitions. And after Mr. Putin ordered the draft of 300,000 additional troops, new conscripts reported being thrown into the fight with minimal training and inadequate equipment. Some were killed after just days in uniform.
The most striking recent failure came on New Year’s Day, when Ukrainian artillery struck a complex housing new Russian soldiers in the Donbas city of Makiivka. The Defense Ministry acknowledged that 89 were killed, but Ukraine claimed casualties in the hundreds.
The hawkish Russian military bloggers — a major source of information on the war in a country where the Kremlin controls the media — blamed Russian commanders: They had concentrated the troops rather than spreading them out, had housed them next to an ammunition depot, and had not prevented soldiers from using cellphones, whose signals the Ukrainians apparently used to zero in on their location.
The criticism leveled at uniformed Russian commanders has created an opportunity for Mr. Prigozhin to portray himself and Wagner as indispensable to the war effort. He seems to be trying to raise his political profile within Russia, though to what end is unclear.
Abbas Gallyamov, a former speechwriter for Mr. Putin who has broken ties with the president, said that Mr. Prigozhin was angling to replace Defense Minister Sergei K. Shoigu, a longtime Putin confidant.
Wagner has become a kind of shadow army for Russia, deployed in support of the Kremlin’s military campaigns in Africa and the Middle East.
A former convicted criminal, Mr. Prigozhin became a restaurateur and befriended Mr. Putin years ago, parlaying that relationship into a varied business empire, including the Wagner Group. He has been indicted in the United States, where he is accused of orchestrating Russian online meddling in the 2016 presidential election.
This year, Mr. Prigozhin has cast off the modest profile he once tried to maintain.
After long denying any role in election meddling, he recently boasted of it. He has criticized the regular military. And, after saying for years that he had no connection to Wagner — he even questioned whether it existed — he acknowledged in September that he was its founder, and has embraced its role in Ukraine.
Mr. Prigozhin has supplemented Russia’s decimated fighting ranks with tens of thousands of prison inmates recruited to his mercenary force, awarded medals, visited military cemeteries and, according to his frequent videos, appeared unexpectedly at the toughest sections of the front line.
In late December, Wagner fighters released a profanity-laden video addressed to the military high command, accusing it of withholding ammunition and causing the deaths of their comrades. Mr. Prigozhin responded to the video by saying “when you’re sitting in a warm office, the frontline problems are hard to hear,” in apparent reference to the generals.
Megan Specia and Ivan Nechepurenko contributed reporting.