A general who commanded forces in Syria is responsible for recent Russian Army advances in Ukraine, western officials said.
Gen Sergei Surovikin is believed to be the strategist responsible for Russian forces “making genuine headway” against two recently captured Donbas cities.
Gen Surovikin, 55, is said by western sources to have used “controversial” tactics against Syrian rebels in his time as the longest-serving Russian commander there.
A few weeks ago, he replaced Gen Alexander Dvornikov, who appeared to have lost the trust of President Vladimir Putin after slow advances and heavy losses in Ukraine.
“Russia has made some significant command changes in recent weeks, notably General of the Army Sergei Surovikin, who has taken over command of the Southern Group of Forces, which is overseeing occupation of southern Ukraine and advances on the Donbas from the south,” a western official said.
“He is a controversial figure, even by the standards of Russian general officers.
“It is unclear whether it’s his influence that has led recent successes around Lysychansk, but certainly there’s been better co-operation among the groups of forces on the Russian side than we saw in the earlier phases of the war.”
Mr Putin on Monday congratulated troops for “liberating” Lysychansk and told them to rest.
The appointment of Gen Surovikin in Syria was a turning point in the conflict, and the government of Bashar Al Assad regained control of more than 50 per cent of the country.
Military analysts attributed advances by Syrian government forces and their allies to the refined but harsh tactics of Gen Surovikin, who became a Hero of the Russian Federation for his leadership.
The official told The National Gen Surovkin's experience as an army officer and a commander of the Russia Air Force made him a significant threat to Ukrainian forces.
“He has run the air service for a period of time, which is unusual for an army general,” the official said.
“It's all about combined arms integration and using the different services in totality to create the effect, and you'd expect from his experience in Syria and across the services this would bring some benefits in that regard. He has a long pedigree.”
On Wednesday, Britain’s Ministry of Defence said that the general’s 30-year career was “dogged with allegations of corruption and brutality”.
The official said the Russians had “regained some momentum in the last few weeks” and “consolidated beyond the defendable line of the Donets River”.
But Ukraine had been fighting a “rear-guard action within a 25-mile [40-kilometre] wide bulge, or salient. Ukrainian forces have now fallen back and it's created a straightened front”.
The fight to hold that line “would likely be particularly influential for the eventual fate of Donetsk oblast”, he said.
“We're paying particular attention to the potential for Sloviansk to become the site of a next major battle.”
But Ukraine’s military had made withdrawal in “relatively good order”, thereby “preserving some of its more capable troops to fight another day”.
Long-range weapons supplied by western powers were having an effect on the Russians but had not yet proved decisive in halting their advance, the official said.