As Kyiv intensifies its calls for longer-range weaponry from the West to help it fight back in the Donbas region, Russian forces are stepping up their assault on the Ukrainian city of Sievierodonetsk, after claiming to have captured the nearby rail hub of Lyman.
Slow, solid Russian gains in recent days point to a subtle momentum shift in the war, now in its fourth month.
The invading forces appear close to seizing all of the Luhansk region of Donbas, one of the more modest war goals the Kremlin set after abandoning its assault on Kyiv in the face of Ukrainian resistance.
On Saturday, local time, Russia's Defence Ministry said its troops and allied separatist forces were now in full control of Lyman, the site of a railway junction, west of the Siverskyi Donets River in the Donetsk region that neighbours Luhansk.
Ukraine's train system has ferried arms and evacuated citizens through Lyman, a key railway hub in the country's east.
Control of that hub also would give Russia's military another foothold in the region. It already has bridges for troops and equipment to cross the Siverskiy Donets river, which has so far impeded the Russian advance into the Donbas.
However, Ukraine's Deputy Defence Minister, Hanna Malyar, said the battle for Lyman continued.
Sievierodonetsk — which lies some 60 kilometres from Lyman on the eastern side of the river, and the largest Donbas city still held by Ukraine — was under heavy assault from the Russians, according to Ukrainian police, who posted on social media on Saturday: "Sievierodonetsk is under constant enemy fire".
Russian artillery was also shelling the Lysychansk-Bakhmut road, which Russia must take to close a pincer movement and encircle Ukrainian forces.
"There was significant destruction in Lysychansk," police said.
On Friday, the governor of Luhansk — which, along with Donetsk, comprises the Donbas — said Russian troops had already entered Sievierodonetsk.
Ukrainian troops may have to retreat from the city to avoid capture, Governor Serhiy Gaidai said.
It was not clear whether they had begun to pull out on Saturday.
On Saturday, Ukraine's General Staff said that multiple Russian strikes had hit communities and infrastructure near Kharkiv, the country's second-largest city.
A solar power station in the region was badly damaged after an apparent missile strike, a Reuters photographer said.
'Donbas will be Ukranian', Zelenskyy says
Also on Saturday, Ukrainian presidential adviser and peace talks negotiator Mykhailo Podolyak repeated a call for deliveries of US-made long-range multiple-rocket launchers.
US officials told Reuters such systems were 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. Ukraine can return Russia behind the Iron Curtain, but we need effective weapons for that," Mr Podolyak tweeted.
President Volodymyr Zelenskyy 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," Mr Zelenskyy said.
In a television interview, Mr Zelenskyy said he believed Russia would agree to talks if Ukraine could recapture all the territory it has lost since the invasion began on February 24.
Still, Mr Zelenskyy ruled out the idea of using force to win back all the land Ukraine has lost to Russia since 2014, including 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.
On Saturday, the Ukrainian military said its troops had repelled eight assaults in Donetsk and Luhansk in the previous 24 hours.
Meanwhile, the British Defence Ministry said in its daily intelligence report that, if Russia succeeded in taking over those areas, the Kremlin would likely view it as a "substantive political achievement", one it could use to justify its invasion to the Russian people.
Shelling keeps medical staff from hospital
Some 90 per cent of buildings in Sievierodonetsk were damaged, Mr Gaidai 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 that information.
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 has said it was waging a "special military operation" to demilitarise Ukraine and rid it of nationalists threatening Russian-speakers there.
Kyiv and Western countries have said 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, either for safer parts of Ukraine or to other countries.
Putin talks with French, German leaders
Pushing diplomatic efforts to find a solution to a conflict that has myriad ramifications beyond Ukraine's borders, French President Emmanuel Macron and German Chancellor Olaf Scholz spoke to Russian President Vladimir Putin in a joint phone call on Saturday.
They urged him to lift the Russian blockade of the port of Odesa to allow Ukrainian grain exports, France said.
The Kremlin said Mr 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 and across Africa.
Meanwhile, the supply of weapons to Kyiv from its allies continued.
Ukrainian Defence Minister Oleksiy Reznikov said the country had started receiving Harpoon anti-ship missiles from Denmark.
Still, Kyiv renewed its calls for greater support.
Deputy Prime Minister Olga Stefanishyna said that NATO had shown itself incapable of mounting a united response to the Russian invasion.
"We have to talk clearly about the catastrophic consequences for the future of all Europe if Ukraine is defeated. It's a shame that, again, we have to recall the results of past 'compromises' with the aggressor," she said in a Facebook post.
Ms Stefanishyna — who is responsible for efforts to integrate Ukraine into Europe — said that, when NATO leaders hold their June 29-30 summit, "it is important to make very concrete and bold decisions aimed at strengthening the alliance and Ukraine's defence capability".