The war of attrition between Russia and Ukraine is killing soldiers at a rate not seen in Europe since World War II.

Ukrainian artillery fire, explosive drones and mines are killing Russian troops as they repeatedly invade no man’s land. While Ukrainian positions are exposed, they are taking heavy casualties from afar from Russian drones, grenades and speedboat bombs.

It is difficult to calculate the scale of casualties, and thus the trajectory of the war: the data is a state secret in both countries. The Ukrainian government has been particularly secretive, limiting access to demographic data that could be used to estimate its losses.

The most complete lists of dead Ukrainian soldiers were compiled by groups abroad with biased or unclear motives.

Working with incomplete information, those groups and other experts estimate that Ukraine has suffered about half of Russia’s irreparable losses — deaths and injuries that take soldiers out of battle indefinitely — in the nearly three-year war.

Russia still wins. A much larger population and more efficient recruitment made this possible compensate for losses to progress more efficiently and gradually, said Franz-Stefan Gady, a military analyst from Vienna.

“Fat is getting thinner. But the thin man dies,” said Mr. Gady.

Counting the dead

The most comprehensive publicly available lists of deaths in Ukraine come from two opaque websites that track obituaries, posthumous medal awards, funeral announcements and other death-related information posted online.

Websites — Lostarmour.info and UALosses.org — produced similar results: each individually counted about 62,000 Ukrainian soldiers who had died since the invasion.

Lostarmour and UALosses say they can only find some of the dead soldiers, because obituaries are published late and some deaths are not published at all. Lostarmour estimates that by December a total of more than 100,000 Ukrainian soldiers had died.

In comparison, Russian researchers and journalists used similar assessment methods that Russia had more than 150,000 people died on the battlefield until the end of November.

The Lostarmour Victims Project is run by about 10 anonymous volunteers, mostly Russian, who scour the Internet and verify information to verify its authenticity, a website spokesman said in an emailed response to questions. The group appears to sympathize with Russia and seeks to discredit Ukrainian propaganda.

A person claiming to run UALosses told The New York Times in an exchange of messages on Xu that he is an IT expert based in a western country who started his project to address a gap in public knowledge. He said he has no ties to Ukraine or Russia and is working anonymously to avoid legal and personal risk. The Times could not confirm that personal information.

The Ukrainian government has accused UALosses of “spreading false information” and appears to block the website from time to time. Lostarmour is blocked in Ukraine, as are all other websites registered in Russia.

The secrecy or ideological bias of websites does not necessarily invalidate their findings. Independent Russian media Mediazona and Ukrainian non-profit organization Book of memories separately verified some UALosses data by taking random samples and comparing them to online obituaries.

A Times statistical analysis of public data from Lostarmour found that at least 95 percent of the group’s entries were correct with a 95 percent certainty and a 5 percent margin of error.

Intelligence assessments

In a rare move, a prominent Ukrainian public figure contradicted his in December country’s official claims for victims.

Independent war correspondent Jurij Butusov announced his 1.2 million YouTube subscribers that sources within the headquarters of the Ukrainian armed forces told him that 105,000 soldiers were “irretrievably lost”, including 70,000 killed and 35,000 missing. It is far more than 43,000 soldiers that President Volodymyr Zelensky claimed were killed from December 8.

Mr. Butusov added that his figure excludes units outside the command of the Armed Forces, such as the National Guard. This would further increase the total number of victims.

A military analyst familiar with Western government estimates of Ukrainian casualties said Mr. Butusov’s figures were credible. The analyst discussed sensitive information on condition of anonymity.

Western intelligence agencies have been reluctant to reveal their internal calculations of Ukrainian casualties for fear of undermining an ally. US officials have previously said that Kiev is hiding this information from even its closest allies.

Rare estimates of Ukrainian losses by Western officials far exceeded Kiev’s official figures. US officials told The Times in 2023 By August of that year, 70,000 Ukrainian soldiers had died. Since then, many of the bloodiest battles of the war have been fought.

Mr. Butusov’s losses rule out serious injury, a key aspect of the military’s combat capability.

Missing in action, and in statistics

Adding to the obfuscation surrounding Ukrainian victims is the large number of soldiers it has declared missing in action.

About 59,000 Ukrainians were registered as missing in December, most of them soldiers, according to Ukraine’s Interior Ministry. Butusov said in December that 35,000 members of the armed forces were missing.

A military analyst familiar with Western assessments said the vast majority of missing Ukrainian soldiers were believed to be dead.

Ukrainian law makes it difficult for relatives of missing men to declare them dead, for inheritance or other purposes. This created a legal purgatory for families whose loved ones were not returned from the battlefield, keeping the death toll artificially low.

Alyona Bondar, a Ukrainian cafe worker, said she had not received any information about her brother, a soldier, since he disappeared on the battlefield in southern Ukraine in 2023.

“It would be better to tell the truth, including for my brother’s sake,” she said in a telephone interview. “It would be better if we had a grave to visit, instead of him lying somewhere in a field for a year and a half.”

Combat deaths are only one aspect of military attrition. A more comprehensive measure is irreparable or irreversible losses: the combined number of deaths and serious injuries that prevent a soldier from fighting again.

What does it mean

Combining the estimates, with their caveats and shortcomings, analysts conclude that Russia loses just under two soldiers to death and serious injury for every Ukrainian fighter who suffers the same fate.

This ratio did not allow Ukraine to overcome Russia’s advantage in population and employment. According to current trends, Ukraine is losing a larger share of its smaller army.

Currently, more than 400,000 Russians are facing about 250,000 Ukrainians on the front line, and the gap between the armies is widening, according to a military analyst familiar with Western estimates.

Russia was able to rebuild and even expand its shattered invasion force by tapping into a population four times the size of Ukraine’s, carrying out the first mobilization since World War II, and recruiting criminals and debtors. The government of Russian autocratic President Vladimir V. Putin is paying increasing rewards to new recruitsand recently started pressing people accused of crimes in the army in exchange for dropping the charges.

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According to Russian financial statistics, these recruiting efforts brought Russia between 600 and 1,000 new fighters a day last year. In that period, Kyiv only briefly reached that rate.

North Korea too sent about 11,000 soldiers to help Moscow’s forces in the Kursk region of southern Russia, where Ukrainians seized territory last summer.

Mr Zelensky’s need to wrestle with public opinion led his government to delay the unpopular draft, then left it scrambling to implement it. Some men are he was hiding to avoid being recruitedor bribed draft officers get an exemption. Ukrainian delay in the recruitment of convicts it produced a small part of fighters who were recruited from Russian prisons.

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The recruiting gap ultimately shapes the battlefield.

Russia is losing more and more people. But every Ukrainian sacrifice brings the Kremlin closer to victory.

Daria Mitiuk and Jurij Šivala contributed to reporting from Kiev and Oleg Macnev from Berlin.