The White House has estimated that Russia's military has suffered 100,000 casualties in the last five months in fighting against Ukraine in the Bakhmut region.
White House national security spokesperson John Kirby told reporters the figure, based on US intelligence estimates, included more than 20,000 dead, half of them from the Wagner mercenary group, which includes convicts released from prison to join the fighting.
"Russia's attempt at an offensive in the Donbas largely through Bakhmut has failed," Mr Kirby said. "Russia has been unable to seize any real strategic and significant territory."
He said the Russians have made some incremental gains in Bakhmut but that this has come at a "terrible, terrible cost" and that Ukraine's defenses in the region remain strong.
"Russia has exhausted its military stockpiles and its armed forces and since December alone, we estimate that Russia has suffered more than 100,000 casualties, including over 20,000 killed in action, nearly half of whom were Wagner soldiers," he said.
"It's really stunning, these numbers," Mr Kirby added, saying the total is three times the number of American casualties in the Guadalcanal campaign in World War II.
Mr Kirby said another US weapons package for Ukraine would be announced soon.
Homes smashed, 34 wounded in Russian strikes on Ukraine
Russia unleashed a fresh volley of missiles on Ukraine overnight, causing huge blazes in a city in the east, damaging dozens of homes and wounding at least 34 people.
The attack on Pavlohrad, a city and rail hub, came during the second wave of nationwide missile strikes in three days, with Moscow apparently reviving its winter tactic of long-range strikes ahead of a planned Ukrainian counter offensive.
A huge crater had been blasted in the backyard of a house that was strewn with debris on Pavlohrad's outskirts. Homes nearby were badly damaged. In the city centre, the windows of a dormitory that serves a chemical plant had been blown out.
"I ran outside and saw the garage was destroyed. Everything was on fire, glass shards were everywhere. Had we been outside, we would have been killed," said resident Olha Lytvynenko, 61.
Viktoriia Suprun, 41, said she had taken cover with her daughter in the hallway of the dormitory.
"We rushed to the hallway, laid on the floor. And then the explosion wave twisted the door. Had we stayed for five more seconds, we would have been trapped here," she said.
"We didn't sleep at night and in the morning. My child will need psychological help, it is horrible," she said.
Mykola Lukashuk, head of the Dnipropetrovsk region council, said the attack had damaged 19 apartment blocks, 25 houses, three schools, three kindergartens and several shops. The 34 wounded included five children, the region's governor said.
The city is located in southeastern Ukraine, behind the main eastern and southern front lines in the war, and includes a railway hub.
Other parts of Ukraine appeared to have survived the wave of strikes unscathed, after air raid sirens sounded for hours through the night. Ukraine said it shot down 15 of 18 incoming cruise missiles.
Officials in the capital Kyiv said there were no reports of civilian casualties or damage there.
A Russian-installed official in occupied Zaporizhzhia region said Russian forces had struck military targets in Pavlohrad. Ukrainian officials said an industrial enterprise was hit, which they did not identify.
The attacks also significantly damaged electricity distribution points in the southern Kherson region and central-eastern Dnipropetrovsk region, leaving thousands of people without power, the Energy Ministry said.
Repairs to the grid were set to take several days, it said in a statement.
The attacks came just three days after Russia killed 23 civilians in a high-rise apartment building in the city of Uman with a missile, part of its first big countrywide volley of airstrikes in nearly two months.
After five months of a Russian assault that secured little new territory despite the bloodiest ground combat of the war, Kyiv is preparing to unleash a counterattack using hundreds of armoured vehicles and tanks supplied by the West.
On Saturday, an apparent Ukrainian drone hit a fuel storage depot in Sevastopol, base of the Russian navy in Crimea, which Moscow seized in 2014.
Kyiv has not directly claimed responsibility but strongly implied it, saying the blaze was part of its preparations for its offensive.
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