Colonel General Oleksandr Syrskyi has been named as the new chief of Ukraine’s army.
Mr Syrskyi has played a key role in some of Ukraine’s biggest victories – but has also faced criticism for some of his tactics.
Here’s what you need to know about Ukraine’s new army chief.
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From Soviet Union to Ukraine
Mr Syrskyi was born in July 1965 in what is now Russia’s Vladimir region, which was then part of the Soviet Union.
He studied in Moscow at the Higher Military Command School – which has produced commanders in both the Russian and Ukrainian armed forces.
Described as an obsessive planner with iron discipline, some military analysts believe his battlefield tactics reflect his hierarchical Soviet training.
He graduated in 1986 and served in the Soviet Artillery Corps, but did not serve in post-Soviet Russia’s army.
Regardless, senior Russian security official Dmitry Medvedev called him a “traitor” on his appointment, accusing him of breaking his oath as an officer.
He moved to Ukraine in the 1980s.
The ‘snow leopard’ who became a Ukrainian hero
Mr Syrskyi has commanded troops against combined Russian forces since 2014, when he earned his call sign “snow leopard”.
They fought a Moscow-backed insurgency in eastern Ukraine using “tactics that were similar to how this cat hunts,” he told Reuters in January.
“This creature is very careful, cunning and courageous.”
Mr Syrskyi became head of Ukraine’s land forces in 2019.
Some of Ukraine’s biggest victories of Russia’s full-scale invasion were overseen by Mr Syrskyi.
He led the successful defence of Kyiv in the war’s early months and was later named a Hero of Ukraine, the country’s highest honour, for his role in repelling Moscow’s advance on the capital.
He was credited with orchestrating a lightning counteroffensive that pushed Russian troops away from the city of Kharkiv and retook swathes of land to the east and southeast.
Mr Syrskyi also led the Bakhmut operation, the war’s longest and bloodiest, which has been criticised because of the high losses suffered by Ukrainian forces.
But he has defended the operation, saying Ukraine’s dogged defence of Bakhmut damaged Russia’s overall war effort by tying down the Wagner mercenary group.
‘Constant innovation’ needed for Ukraine to win
On his first full day in the job, Mr Syrskyi said Ukraine’s path to victory was reliant on constant innovation in the way it fights the war, highlighting technology like drones and electronic warfare.
He also promised to protect the lives and health of Ukrainian forces and ensure reliable logistics.