Russia claimed on Tuesday to have captured a village on the northern outskirts of the city of Bakhmut, which it is attempting to surround in a big push for what would be its biggest prize in Ukraine since last summer.
There was no immediate response from Kyiv to Moscow's claim about the village of Blahodatne, and Reuters was not immediately able to verify the situation there. It came three days after the head of Russia's Wagner Group said the mercenary force had seized the village in an attack Kyiv said it had repelled.
The village, which sits on one of the main roads into Bakhmut, about 5km (3 miles) north, was captured with the help of aerial support, Moscow's defence ministry said in a statement.
Moscow has made clear, if gradual, advances in the area in recent weeks, notably capturing the salt-mining town of Soledar to Bakhmut's north.
Were it to force Ukraine to withdraw from the city that once held 75,000 people, it would be Moscow's first big prize since it took the similarly-sized cities of Sievierodonetsk and Lysychansk in July.
During the fighting for Bakhmut, two civilians, a boy and a 70 year-old-man, were killed in a Russian artillery attack on Tuesday, regional governor Pavlo Kyrylenko said. Four others were wounded in the attack, he said.
Separately, a large Russian force has launched an assault against the Ukrainian-held bastion of Vuhledar this week, further south along the same eastern front. Russian officials have claimed to have gained a foothold there, while Kyiv says it has largely repelled that attack so far.
Britain's Ministry of Defence said the Russian force in the new Vuhledar assault was at least the size of a brigade, a unit typically comprising several thousand troops.
The Russians had advanced hundreds of metres across a river toward Vuhledar and could make more localised gains there, the ministry said in an unusually detailed daily intelligence update. It said the assault on Vuhledar was unlikely to lead to a significant breakthrough, but could be intended to draw Ukrainian effort away from defending Bakhmut.
Despite weeks of intense trench warfare that both sides have compared to a meat grinder, frontlines in eastern Ukraine had largely been frozen in place since November after Kyiv recaptured swathes of territory in the second half of 2022.
But momentum has lately swung back towards Russia, making substantial gains for the first time since the middle of last year.
Military experts say Moscow appears determined to push forward in the coming months before Kyiv receives hundreds of newly pledged Western tanks and armoured vehicles for a counter-attack to recapture occupied territory this year.
Ukrainian President Volodymyr Zelensky described Russia's assault in the east as an attempt to exact "revenge" for earlier losses.
"And I think that they will not be able to provide their society with any convincing positive result in the offensive. I am confident in our army. We will stop them all, little by little, destroy them and prepare our big counteroffensive," he said on Monday.
Kyiv says the Russian assaults of recent weeks have come at huge cost, initially mostly relying on Wagner mercenaries, including thousands of convicts recruited from Russian prisons and sent into battle in waves with little training or equipment.
But Russia's call-up of hundreds of thousands of reservists late last year means Moscow has now been able to reconstitute regular military units exhausted or depleted earlier in the war.
Western military experts say Bakhmut is not by itself of major strategic importance. But it is is one of just a handful of substantial cities in Ukraine's eastern Donbas region that are still under Ukrainian control, and Moscow now says capturing the full Donbas is a main objective of the "special military operation" it ordered 11 months ago.
F-16: Biden says no
Since winning the Western pledge for tanks after months of lobbying, Kyiv has pressed on with further requests for arms, including calls for jet fighters such as US F-16s. Neither side has been able to secure control of the skies over Ukraine.
The West has so far refused to send weapons that could be used to attack deep inside Russia, a line countries still seem unwilling to cross. US President Joe Biden responded with a flat "No" when asked by reporters at the White House on Monday if Washington would send F-16s.
Still, Ukraine has held out hope. Defence Minister Oleksiy Reznikov was due in Paris on Tuesday to meet President Emmanuel Macron, who told reporters in The Hague on Monday that "nothing is excluded" when it comes to military assistance.
Macron said any move to send jets would depend on factors including the need to avoid escalation and assurances the aircraft would not "touch Russian soil".
Polish Prime Minister Mateusz Morawiecki also did not rule out a possible supply of F-16s to neighbouring Ukraine, in response to a question from a reporter before Biden spoke.
Morawiecki said in remarks posted on his website that any such transfer would take place "in complete coordination" with Nato. Poland has long pushed for more aggressive military support for Ukraine.
British Prime Minister Rishi Sunak's spokesperson said on Tuesday London did not believe its own jets would be useful.
"The UK's... fighter jets are extremely sophisticated and take months to learn how to fly. Given that, we believe it is not practical to send those jets into Ukraine," the spokesperson told reporters.