A column of smoke rises from burning fuel tanks that locals said were hit by five rockets at the Vasylkiv Air Base, following Russia's invasion of Ukraine, outside Kyiv, Ukraine, March 12, 2022.
A column of smoke rises from burning fuel tanks that locals said were hit by five rockets at the Vasylkiv Air Base, following Russia's invasion of Ukraine, outside Kyiv, Ukraine, March 12, 2022. Reuters / THOMAS PETER

Russian forces intensified their assault on the largest city held by Ukrainian forces in the Donbas region in the east on Sunday as Kyiv said it was hopeful longer-range weapons it desperately needs from Western allies could soon arrive.

Slow, solid Russian gains in recent days in eastern Ukraine's Donbas, comprising the Luhansk and Donetsk regions, point to a subtle momentum shift in the war, now in its fourth month.

Invading forces appear close to seizing all of the Luhansk region, one of the more modest war goals the Kremlin set after abandoning its assault on the capital, Kyiv, in the face of Ukrainian resistance.

Russia's defence ministry said its troops and allied separatist forces were in full control of Lyman, the site of a railway junction west of the Siverskyi Donets River in the Donetsk.

However, Ukraine's deputy defence minister, Hanna Malyar, said the battle for Lyman continued, the ZN.ua website reported.

Sievierodonetsk, some 60 km (40 miles) northeast of Lyman on the eastern side of the river and the largest Donbas city still held by Ukraine, was under heavy assault.

"The situation has extremely escalated," said Serhiy Gaidai, the governor of Luhansk.

The shelling was so intense it was not possible to assess casualties and damage, though two people were killed on Saturday and 13 more buildings in the city were destroyed, he said.

Gaidai said on Friday that Ukrainian troops might have to retreat from the city to avoid capture but it was not clear whether they had begun to pull out.

Russian artillery was also pounding the Lysychansk-Bakhmut road, which Russia must take to close a pincer movement and encircle Ukrainian forces, and police said there was "significant destruction" in Lysychansk.

Reuters could not independently verify the accounts.

Ukrainian presidential adviser and peace negotiator Mykhailo Podolyak repeated a call for U.S.-made long-range multiple-rocket launchers. U.S. officials have told Reuters such systems are actively being considered, with a decision possible in coming days.

"It is hard to fight when you are attacked from 70 km away and have nothing to fight back with ... we need effective weapons," Podolyak posted on Twitter.

President Volodymyr Zelenskiy voiced hopes in a late-night video address that Ukraine's allies would provide needed weapons, adding that he expected "good news" in the coming days.

His adviser, Oleksiy Arestovych, said: "The weapons we so desperately need will most likely be delivered soon."

Ukraine has started receiving Harpoon anti-ship missiles from Denmark and U.S. self-propelled howitzers, Ukrainian Defence Minister Oleksiy Reznikov said on Saturday.

'CATASTROPHIC CONSEQUENCES'

Zelenskiy said the military situation in the Donbas was very complicated, adding that defences were holding up in a number of places, including Sievierodonetsk and Lysychansk.

"It's indescribably difficult there. And I am grateful to all those who withstood this onslaught," he said.

Analysts at the Washington-based Institute for the Study of War said if Russian forces were to capture Sievierodonetsk, Ukraine could be expected to launch counter-offensives.

"Putin is now hurling men and munitions at the last remaining major population centre in that (region) ... as if taking it would win the war for the Kremlin. He is wrong," they said.

In a sign of frustration over Western differences on the war as its economic costs become more evident, Ukrainian Deputy Prime Minister Olga Stefanishyna said NATO had shown itself incapable of mounting a united response.

"We have to talk clearly about the catastrophic consequences for the future of all Europe if Ukraine is defeated," she said on Facebook.

Pushing diplomatic efforts for a solution to a conflict that has ramifications beyond Ukraine's borders, French President Emmanuel Macron and German Chancellor Olaf Scholz spoke to Russian President Vladimir Putin in a call on Saturday.

They urged him to lift a Russian blockade of Odesa port to allow Ukrainian grain exports, France said. The Kremlin said Putin told them Moscow was willing to discuss ways to make it possible for Ukraine to resume shipments of grain from Black Sea ports.

Ukraine is a major grain exporter, and the blockage of its exports threatens to result in food shortages in a number countries, including in Africa.

Zelenskiy said in a television interview he believed Russia would agree to talks if Ukraine could recapture all the territory it has lost since the invasion began on Feb. 24.

Still, Zelenskiy ruled out the idea of using force to win back all the land Ukraine has lost to Russia since 2014, which includes the southern peninsula of Crimea, which Moscow annexed that year.

"I do not believe that we can restore all of our territory by military means. If we decide to go that way, we will lose hundreds of thousands of people," he said.

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

Thousands of people, including many civilians, have been killed and several million have fled their homes, either for safer parts of Ukraine or to other countries.