Tensions spilled into public last November when the general described the war as a “stalemate” in an interview with The Economist – a statement instantly derided by Mr Zelensky and his camp.

Around the same time, the president’s office removed one of Gen Zaluzhny’s deputies and sacked the head of Ukraine’s medical forces with little explanation.

A month later, the Ukrainian president publicly rebuffed the former commander’s plea to mobilise 500,000 new soldiers.

Prof David Silbey, a military historian at Cornell University, said Gen Zaluzhny had become a scapegoat for the lack of recent military successes.

“Generals in war are like managers in baseball: often blamed for things out of their control. Zaluzhny seems to be taking the fall for the failure of Ukraine’s fall offensive and Russia’s retaking of the military initiative,” he said.

US aid package under threat

The move comes at a perilous time for Ukraine, with Joe Biden, the US president, still struggling to garner enough support for a $60 billion (£47.56 billion) aid package for Kyiv.

The US Senate on Thursday voted to move ahead with a stripped-down bill after Republicans rejected a combined border security and foreign aid deal after Donald Trump, the party’s presidential hopeful, trashed it.

Democrat Chuck Schumer, the senate majority leader, proposed the “Plan B” to keep funding for Ukraine alive.

The decision to name Gen Syrsky as Zaluzhny’s successor may not be a popular one within Ukraine’s military, with troops holding him responsible for the bloody and ultimately fruitless defence of Bakhmut.

Thousands of soldiers died trying to hold on to the remains of the ruined city in eastern Ukraine against hordes of Wagner mercenaries, with many arguing that they should have withdrawn earlier.

Gen Syrsky said his approach had blunted the Russian war effort and neutralised the offensive threat posed by Wagner.

One Ukrainian soldier described him as a “butcher”, adding he and his comrades were “all meat now”.

Another source close to the Ukrainian military said “he’s not liked”, but acknowledged Gen Zaluzhny’s position had become untenable after a “failed counter-offensive and zero progress for months”.

Gen Syrsky saw off competition from General Kyrylo Budanov, the maverick head of Ukraine’s military intelligence, General Oleksandr Pavliuk, a former deputy defence minister, and General Sergiy Shaptala, former head of the general staff, for the role.