Russian troops keep coming in waves along the frontline in eastern Ukraine, Ukrainian soldiers said on Tuesday, as President Vladimir Putin reaffirmed his view that Russia's very existence as a state was at stake in the war.
In the eastern Donbas region, Russia and Ukraine are locked in the bloodiest infantry battle in Europe since World War Two, after Moscow launched a winter offensive with hundreds of thousands of freshly called up reservists and mercenaries.
Putin has framed Moscow's year-long invasion as a defensive pushback against what he sees as a hostile West bent on expanding into territories historically ruled by Russia.
"So for us this is not a geopolitical task, but a task of the survival of Russian statehood, creating conditions for the future development of the country and our children," he said during a visit to an aviation factory in Buryatia, some 4,400 km (2,750 miles) east of Moscow.
Putin accuses the West of using Ukraine as a tool to inflict "stragetic defeat" on Russia. Kyiv and its Western allies say Moscow is waging an unprovoked war of imperial conquest that has destroyed Ukrainian cities, killed thousands of people and forced millions more to flee their homes.
'Very painful' in the east
Frontlines have barely budged in more than four months of Russia's winter offensive despite huge losses on both sides.
With assaults elsewhere on the front having failed, Russia appears determined to secure the ruins of the small city of Bakhmut in what would be its first victory since mid-2022.
In an overnight video address, President Volodymyr Zelensky said Ukraine's "future is being decided" in battles in the east, including Bakhmut, where Ukrainian commanders say they are killing enough Russian attackers to justify staying and fighting for a ruined city that has nearly been surrounded.
"It is very tough in the east - very painful," Zelensky said. "We have to destroy the enemy's military power. And we shall destroy it."
Further north on the frontline near Kreminna, Oleksandr, 50, commander of a unit in Ukraine's 110th battalion, said Russian assaults were still relentless despite having claimed little ground there. The Russians are trying to edge back towards Lyman, a major transit hub Ukraine recaptured last year.
"They are pushing hard. They are lobbing mortar bombs at us," Oleksandr told Reuters, describing Russian units advancing in three-man fire teams, with another wave behind them sent to replace them when they are killed.
"At night they always attack on foot and we sit, looking through our thermal goggles, and shooting them."
The Kremlin, for its part, said Kyiv must accept "new realities" - its shorthand for Russia's claim to have annexed nearly a fifth of Ukraine.
"We have to achieve our goals. Right now this is only possible by military means due to the current position of the Kyiv regime," Russian state news agencies quoted Kremlin spokesman Dmitry Peskov as saying.
Denis Pushilin, the administrator of Russian-controlled parts of Ukraine's Donetsk region, said battles for "every meter" of Bakhmut were taking place.
"We can see that the Ukrainian regime absolutely does not take into account the numerous losses in the (Ukrainian town of) Soledar and the direction of Bakhmut. In fact, with its orders, it grinds down its own soldiers," Pushilin was quoted as saying by the RIA news agency.
Moscow's ammunition shortage
After recapturing swathes of territory in the second half of 2022, Kyiv has kept mainly to the defensive over the past four months, while Moscow has launched its big winter offensive using its freshly mobilized reservists and convicts recruited from jail as mercenaries.
Ukrainian officials say they are preparing their own counter-offensive for later this year, once muddy ground dries up and hundreds of Western tanks and armored vehicles arrive.
But the outcome of those campaigns could depend on which side emerges stronger after Russia's winter assault.
Britain's Ministry of Defence said on Tuesday that Moscow was running short of ammunition, "to the extent that extremely punitive shell-rationing is in force on many parts of the front."
"This has almost certainly been a key reason why no Russian formation has recently been able to generate operationally significant offensive action," it said in a daily intelligence update.
But Ukraine is also facing shortages of shells, and ultimately has a smaller population to commit to a battle of attrition. Some military experts say Bakhmut is unfavorable ground for Kyiv to fight on, against Russian forces that have advanced far enough around the city to hit Ukrainian supply lines in the rear.
"We could lose here everything we wanted to use for those counter-offensives," Ukrainian military analyst Oleh Zhdanov said of the battle for Bakhmut.
Both sides reported fresh civilian casualties near the front.
Zelensky said six high-rise buildings were hit in the center of Kramatorsk by a Russian missile, killing at least one person and wounding three. On the Russian-occupied side, in Volnovakha further south, the body of a woman lay on a street next to a ruined shop. A Russian military investigator told Reuters the area was hit by Ukrainian shells.
Off the battlefield, negotiators hit a snag in talks to extend the Black Sea grain deal, brokered by the UN and Turkey to prevent global famine by securing wartime exports from Ukraine and Russia, both among the world's top food suppliers.
The agreement expires this week. Russia said it had agreed to let it be extended for 60 days, in what the Kremlin called a gesture of "goodwill," but would block any further extension unless it received more guarantees from the West for exports of its own fertilizer and crops.
Kyiv rejected the 60-day extension, saying the agreement allows extensions only of 120 days. It says a shorter duration would not be long enough to organize new grain shipments.