Ukrainian President Volodymyr Zelenskyy has replaced his top army general in a major shake-up of the country’s war strategy as the conflict with Russia grinds into its third year.

In a post on X, formerly Twitter, Mr Zelensky thanked Valerii Zaluzhnyi for his two years of service and discussed possible replacements for the top military job.

“The time for such a renewal is now,” Mr Zelensky said.

Mr Zelensky then appointed Oleksandr Syrskyi, the commander of Ukraine’s ground forces, to lead the army. Colonel general Syrskyi, 58, has been involved in the Ukrainian army’s effort to adopt NATO standards since 2013.

In a Telegram message, General Zaluzhnyi did not announce he had stepped down but said he accepted that “everyone must change and adapt to new realities” and agreed that there is a “need to change approaches and strategy” in the war.

The move followed days of speculation spurred by local media reports that Mr Zelensky would sack General Zaluzhnyi, who was highly regarded by his troops and by foreign military officials. Mr Zelensky’s office and the Defence Ministry denied the rumours.

Some analysts have warned that General Zaluzhnyi’s exit could bring unwelcome disruption, potentially driving a wedge between the Ukrainian army and politicians, and fuelling uncertainty among Kyiv’s Western allies.

Born into a family of Soviet servicemen, General Zaluzhnyi is credited with modernising the Ukrainian army along NATO lines. He took charge seven months before Russia’s full-scale invasion.

He earned broad public support after the successful defence of Kyiv in the early days of the war, followed by a triumphant counter-offensive in the Kharkiv region and the liberation of Kherson.

“We are on our land and we will not give it up,” General Zaluzhnyi said on the first day of the war.

Retired Australian major general Mick Ryan, a fellow of the Centre for Strategic and International Studies think tank in Washington, described General Zaluzhnyi as “a charismatic and popular military leader” who would be hard to replace.

His replacement will have to build personal relationships with US and NATO military chiefs while the perception of government instability “is a real danger area for” Mr Zelensky, Ryan wrote recently in an article posted online.

Meanwhile, Ukrainian forces claimed to have shot down a Russian attack helicopter in eastern Ukraine near the city of Avdiivka, where soldiers are fighting from street to street as Russia’s army steps up its four-month campaign to surround Kyiv’s defending troops.

Ukrainian soldiers used a portable anti-aircraft missile to take down the Ka-52 Alligator attack helicopter, one of the Russian air force’s deadliest weapons, according to Oleksandr Tarnavskyi, the commander of Ukrainian units fighting on the south-eastern front line.

The roughly 1,500-kilometre (930-mile) line of contact has shifted little during recent months of wintry weather.

But as the war in Ukraine nears its two-year anniversary, Avdiivka has become “a primary focus” of Moscow’s forces, the U.K. Defense Ministry said in an assessment Thursday.

Street-to-street combat is taking place in the city as Ukrainian troops seek to keep their main supply route open amid intense bombardment, the ministry said on X.

The General Staff of Ukraine’s armed forces reported on Thursday that its troops had fended off 40 enemy assaults around Avdiivka over the previous 24 hours.

That is roughly double the number of daily Russian assaults at other points along the front line.

Russia’s Pravda newspaper reported on Thursday that the Russian army was attempting to cut a key logistics supply route for Ukraine in the village of Lastochkyne, about 6 kilometres (4 miles) west of Avdiivka.

The Russian military has used electronic warfare to take out the Starlink communications system which Ukrainian troops use to communicate, Pravda said.

Ukraine has built multiple defences in Avdiivka, complete with concrete fortifications and a network of tunnels.

Despite massive losses of personnel and equipment, Russian troops have slowly advanced since October.

The fight has evolved into a gruesome effort for both sides. It has been compared to the nine months of fighting for Bakhmut, the Ukraine war’s longest and bloodiest battle.

It ended with Russia capturing the bombed-out, deserted city last May in what Moscow hailed as a major triumph.

Both Bakhmut and Avdiivka are located in Ukraine’s Donetsk region.

Moscow-backed rebels seized part of the region in 2014 and Russia illegally annexed all of it in 2022 with three other Ukrainian regions.

Russia wants to capture the entire Donetsk region, where it currently holds just over half of the territory.