One million people have been killed or injured in the war between Russia and Ukraine.

Establishing the exact number of dead and injured in the conflict is difficult. Russia and Ukraine refuse to release official estimates and sometimes publish figures that many people distrust.

A confidential Ukrainian estimate from earlier this year puts the number of Ukrainian soldiers killed at 80,000 and the number injured at 400,000, people familiar with the matter say. Western intelligence estimates of Russian casualties vary, with some putting the figure at nearly 200,000 dead and around 400,000 injured.

The losses are a problem for Russia as it tries to push into eastern Ukraine with waves of poorly trained soldiers while fending off a recent Ukrainian incursion in the Kursk region. But they are far more damaging for Ukraine, whose population is less than a quarter of that of its giant neighbor.

The high – and rapidly rising – casualty numbers on both sides underscore the devastating long-term consequences for countries that were struggling with population declines before the war, largely due to economic turmoil and social unrest. They also illuminate one of Russian President Vladimir Putin's motivations for launching the invasion in 2022: to increase Russia's population by absorbing Ukrainians. Russia's invasions and seizure of Ukrainian territory over the past decade have resulted in Ukraine losing at least 10 million people to occupation or as refugees, according to government and demographer estimates.

Putin has long identified combating Russia's chronic population decline as a priority. The Kremlin has since launched a campaign to Russify the occupied territories, which includes the mass abduction of children and pressure on Ukrainians to accept Russian citizenship. In the occupied Donbass region, Russian citizenship is now required for property sales and other transactions.

Modern-day Ukraine was once part of the Russian Empire, and Putin has repeatedly stated that he wants to return the country to that state. He denies Ukrainian identity and statehood, claiming that Ukrainians, a largely Slavic and Orthodox Christian people, are in fact part of the Russian nation.

“Demography is a priority for Putin, and he wants to use Ukraine and its people to consolidate Russia's Slavic core,” said Ivan Krastev, a Bulgarian-born political scientist and author of a forthcoming book on European demography. “But for Ukraine, the dilemma is existential: How many people can you lose in a war without losing your future?”

Putin's most effective measure to increase Russia's population before a full-scale invasion was the annexation of Crimea from Ukraine in 2014. According to Krastev, who bases his estimates on the latest Russian census, this brought about 2.4 million people to Russia.

Although Russia was able to gain population through territorial gains, the war had a devastating impact on the population structure and the labor market. Since the start of the large-scale invasion, well over 600,000 Russians have fled the country. These are mainly young and aspiring professionals who could afford to move abroad and start a new life.

Russia has traditionally relied on labor migration from Central Asia, but the war reduced the flow of migrant workers and in some cases even reversed it. This exacerbated Russia's growing labor shortage as Siberia and the Far East are rapidly depopulating. Pro-government experts have publicly floated the idea of ​​importing workers from North Korea.

Russia's attacks on Ukraine have had a disastrous impact on the neighboring country's population. The most recent census in 2001 recorded 48 million inhabitants. By early 2022, before the Russian invasion, that number had fallen to 40 million, according to Ukrainian demographers and government officials, including regions such as Crimea, which Russia occupied in 2014. With over six million people having fled Ukraine since the war began in February 2022, according to the United Nations, and Russia seizing more land, the total population in Kyiv-controlled territory has now fallen to 25-27 million, according to previously unpublished Ukrainian government estimates.

Oleksandr Gladun, a researcher at the Ptoukha Institute of Demography, estimates the pre-war population of the whole of Ukraine at 42 million, while at the beginning of this year around 29 million people lived in state-controlled territory. Ukraine's population can only be calculated several years after the end of the war, when the number of returnees is known, he said.

The impact could be long-lasting. In addition to the deaths among soldiers, Ukraine's birth rate has also fallen to its lowest level since records began: in the first half of this year, three times as many people died as were born, according to government data. During this period, around 250,000 deaths and over 87,000 births were registered, according to government data, which is 9% less than in the same period last year. In 2021, the year before the large-scale invasion, over 130,000 births were registered.

Russia's warfare also aims to make Ukraine uninhabitable. Russian missile and drone attacks have paralyzed large parts of Ukraine's energy network, including power plants. If there are major power and heating outages this winter, many more Ukrainians could flee abroad.

The Ukrainian government, like the Russian one, keeps the number of war casualties secret. President Volodymyr Zelensky said in February that around 31,000 soldiers had been killed so far. Several former politicians and security officials said this underestimation was mainly to appease society and encourage the mobilization of urgently needed new recruits. A spokesman for Zelensky declined to comment.

One of the main reasons Zelensky is not mobilizing the key group of men aged 18 to 25 – who normally make up the bulk of any combat force – is that most of these people do not yet have children, according to former Ukrainian officials. If recruits in this age group die or become disabled, the future demographic outlook would worsen even further, Ukrainian demographers say.

Ukraine has therefore defied calls from Western partners to send more men into battle and has only carried out a partial mobilization. The average age of Ukrainian fighters is now over 43, according to estimates by government and military officials. Kyiv has recruited a small number of convicts and foreigners to increase the number of fighters.

The number of civilian deaths is unknown. Russia's capture of the southeastern port city of Mariupol in 2022 alone claimed more than 8,000 lives, according to estimates by the non-governmental organization Human Rights Watch.

Ievgeniia Sivorka contributed to this article.

Write to Bojan Pancevski at [email protected]