When Russia seized Crimea in 2014, about 400 Russian soldiers were killed during the month-long campaign, the losses of which stirred up Russian public opinion.
But Russia is losing that number almost every day during its current invasion of Ukraine, according to what the New York Times quoted US and European officials as saying.
The newspaper says that the growing death toll from Russians reveals a potential weakness in Russian President Vladimir Putin’s military strategy.
On Tuesday, the US Department of Defense announced that some Russian units had laid down their weapons and refused to fight, and that other units were deliberately damaging their military vehicles.
State Department spokesman John Kirby said the Ukrainian resistance was making a “real difference” on the ground.
For example, US officials were expecting the northeastern city of Kharkiv to fall in one day, but Ukrainian forces retook control of it despite the massive bombing that targeted it.
On Wednesday, the Pentagon denied the fall of the city of Kherson, after Russia announced its control, and said that the convoy heading to Kyiv was experiencing logistical difficulties that disrupted it.
Video clips, according to the newspaper, showed the bodies of Russian soldiers in the areas around Kharkiv and the charred remains of tanks and armored vehicles, and their crews, dead or wounded.
The newspaper published pictures of some of the bodies.
The Russian Defense Ministry admitted for the first time, on Sunday, that there were dead and wounded, but did not provide numbers.
Neither party’s claims have been independently verified, and Biden administration officials refused to publicly discuss casualty figures, but a US official estimated Russian losses as of Monday at 2,000, an estimate that two European officials agreed with.
The three spoke to the newspaper, asking not to be named.
Senior Pentagon officials said at special briefings in Congress that the deaths were on Monday, 1,500 on each side in the first five days of the conflict.
By way of comparison, nearly 2,500 US soldiers have been killed in Afghanistan over the 20-year war.
For Mr. Putin, the rising death toll could damage any remaining domestic support for his Ukrainian endeavour.
“If Russian losses were of such magnitude, it would be difficult for Putin to justify them to his people,” James Stavridis, who was the supreme commander of NATO forces before his retirement, was quoted as saying by the newspaper.
In particular, Pentagon officials and military analysts said, it is surprising that Russian soldiers have left the bodies of their comrades behind.
Ukrainian authorities have launched a website they say is aimed at helping Russian families track down information about soldiers who may have been killed or captured.
The site, which states that it was created by the Ukrainian Interior Ministry, says that it presents videos of captured Russian soldiers, some of whom were wounded, and the site says, “If your relatives or friends are in Ukraine and participated in the war against our people, here you can get information about their fate.”
The site, 200rf.com, is a grim reference to the word “cargo 200,” a military symbol the Soviet Union used to refer to the bodies of soldiers placed in zinc-lined coffins for transport away from the battlefield.
The site is part of a campaign by Ukraine and the West to counter what US officials describe as Russian disinformation that includes Russia’s insistence before the invasion that forces surrounding Ukraine were simply there to conduct military maneuvers.
On Monday, Ukraine’s ambassador to the United Nations, Sergei Kisletsya, read out what he described as the final text messages from a Russian soldier to his mother.
He said that Ukrainian forces obtained it after the killing of the soldier, who wrote, “We were told they would welcome us but they would fall under our armored vehicles, throw themselves under the wheels and not let us pass.”
A Biden administration official said photos of body bags or coffins, or soldiers killed and left on the battlefield, would prove most damaging to Mr. Putin at home.
Ukrainian officials are using reports and photos on social media of Russian casualties in an attempt to undermine the morale of the invading Russian forces.
On Monday, Ukrainian Defense Minister Oleksiy Reznikov offered Russian soldiers money and an amnesty if they surrendered.