Oleksiy Arestovych, a military adviser to Ukraine‘s president, said “preliminary information” suggested Gen Gerasimov had been removed from his post while Vladimir Putin and his inner circle assessed whether he should be allowed to continue to lead the country’s armed forces.
There has been no official confirmation of the reported sacking, although speculation about a purge of senior military commanders increased after Gen Gerasimov was absent from Russia’s annual Victory Day parade on Monday.
Russian armed forces have suffered several major setbacks in their war, failing to take Kyiv early on and enduring heavy losses – both in lives and equipment.
In the wake of their failure to seize the capital, Russian forces pulled back and regrouped – and switched their focus to Ukraine’s eastern Donbas, a region where Moscow-backed separatists have fought Ukrainian troops for eight years.
But Russia’s advance there has been slow, too, and Western officials say Russia has not managed to take any cities.
One of the most dramatic examples of Ukraine’s ability to prevent easy victories is in Mariupol, where Ukrainian fighters holed up at a steel plant have denied Russia full control of the city.
A lack of Russian gains has led to speculation that Mr Putin is planning a purge of military leaders who are being blamed for the failures.
Reports said a Telegram channel run by the Ukrainian interior ministry had claimed that two more commanders had been sacked due to battlefield losses.
The Telegram feed alleged that the Commander of the Black Sea Fleet, Admiral Igor Osipov, had been removed from his post and arrested, while the Commander of the 6th Army, Lieutenant General Vladislav Ershov, had reportedly been fired, along with the commander of the tank army of the western military district, Lieutenant General Sergei Kisel and one of the deputy commanders, [and] Commander of the 22nd Army Corps of the Southern Military District, Major General Arkady Marzoev.
Ben Wallace, the British defence secretary, said last week that Russian military chiefs were “terrified they are about to be purged and pushed out”.
“Be careful if you’re out in sole command of something in the Russian system, because it may not be for long,” Mr Wallace said.
“There is a point of tension in the system. As much as they respect the former KGB man [Mr Putin] for being a strong leader, the Russian general staff are going to be made scapegoats for his mess.”