A view shows apartment buildings damaged during Ukraine-Russia conflict in the town of Popasna in the Luhansk region, Ukraine May 27, 2022.
A view shows apartment buildings damaged during Ukraine-Russia conflict in the town of Popasna in the Luhansk region, Ukraine May 27, 2022. Reuters / ALEXANDER ERMOCHENKO

Russia said its forces were in full control of the Ukrainian town of Lyman, a railway hub in the Donetsk region, on Saturday in a gain that would help set the stage for the next phase of the Kremlin's offensive in the eastern Donbas.

Ukrainian and Russian forces had been fighting for Lyman for several days. The town lies 40 km (30 miles) west of Sievierodonetsk, the largest Donbas city still held by Ukraine but now under heavy assault from Russian forces.

The governor of Luhansk region, which along with Donetsk makes up the Donbas, said on Friday Russian troops had entered Sievierodonetsk, focus of the main Russian offensive.

The Russian gains indicate a shift in momentum in the war.

Although the forces that invaded Ukraine on Feb. 24 failed to capture the capital Kyiv in the conflict's early stage, they are making slow but steady advances in the Donbas, large parts of which were already controlled by Moscow-backed separatists before the war.

The tactics involve mass artillery bombardments and air strikes that have laid waste to towns and cities.

"If Russia did succeed in taking over these areas, it would highly likely be seen by the Kremlin as a substantive political achievement and be portrayed to the Russian people as justifying the invasion," the British defence ministry said in its daily intelligence report on Saturday.

The British report said Russian forces had "likely" captured most of Lyman, and the Russian Defence Ministry said later on Saturday they had taken full control of the town.

Russia also said on Saturday it had used missile strikes to destroy Ukrainian command posts in Bakhmut and Soledar. Both towns lie on an important road running southwest from Lysychansk and Sievierodonetsk.

Lyman is a railway junction and also the gateway to rail and road bridges over the Siverskyy Donets River.

The British briefing said a bridgehead near Lyman would give Russia an advantage in the potential next phase of the Donbas offensive. Russian forces were likely to attempt to cross the river in the coming days, it said.

The General Staff of Ukraine's armed forces said on Saturday Ukrainian forces had repelled eight assaults in Donetsk and Luhansk in the previous 24 hours. Russia's attacks included artillery assaults in the Sievierodonetsk area "with no success", it said.

BUILDINGS DESTROYED

The Luhansk governor, Serhiy Gaidai, said on Friday that Ukrainian forces may have to retreat from Sievierodonetsk - which lies on the eastern side of the river - to avoid capture after Russian troops entered it.

Some 90% of buildings in Sievierodonetsk were damaged, he said, with 14 high-rise buildings destroyed in the latest shelling. Several dozen medical staff were staying on in Sievierodonetsk but they faced difficulty just getting to hospitals because of the shelling, he said.

Reuters could not independently verify the information.

President Volodymyr Zelenskiy remained defiant in his nightly address to Ukrainians.

"If the occupiers think that Lyman and Sievierodonetsk will be theirs, they are wrong. Donbas will be Ukrainian," Zelenskiy said.

Analysts at the Washington-based Institute for the Study of War said that while Russian forces had begun direct assaults on built-up areas of Sievierodonetsk, they were likely to struggle to take ground in the city itself.

"Russian forces have performed poorly in operations in built-up urban terrain throughout the war," they said.

Russia says it is waging a "special military operation" to demilitarise Ukraine and rid it of nationalists threatening Russian-speakers there. Kyiv and Western countries say Russia's claims are a false pretext for war.

Thousands of people, including many civilians, have been killed and several million have fled their homes in the war. Russian destruction of whole urban areas has drawn widespread international condemnation, although Moscow denies targeting civilians.

Russian President Vladimir Putin has not been deterred by a broad range of Western sanctions on Russia, nor by earlier battlefield setbacks.

OIL DILEMMA

Russian troops advanced after piercing Ukrainian lines last week in the city of Popasna, south of Sievierodonetsk, and capturing several nearby villages.

Russia's eastern gains follow the withdrawal of its forces from approaches to Kyiv, and a Ukrainian counter-offensive that pushed its forces back from Ukraine's second city, Kharkiv.

Ukraine's General Staff said on Saturday that multiple Russian strikes had hit nearby communities and infrastructure near Kharkiv.

In the south, where Moscow has seized a swath of territory since the invasion, including the port of Mariupol, Ukrainian officials say Russia aims to impose permanent rule.

On the diplomatic front, European Union officials said a deal might be reached by Sunday to ban deliveries of Russian oil by sea, accounting for about 75% of the bloc's supply, but not by pipeline.

Zelenskiy has criticised the EU for delaying such a ban. But his country has also received a steady supply of weapons from allies. In the latest such delivery, Ukrainian Defence Minister Oleksiy Reznikov said on Saturday Ukraine has started receiving Harpoon anti-ship missiles from Denmark and self-propelled howitzers from the United States.