More than 2 million Russian and Ukrainian troops have been killed or wounded since Russia invaded Ukraine in February 2022, according to a study released Wednesday by the Center for Strategic and International Studies and published by The New York Times.
The study underscores the human cost of a war that has increasingly become one of attrition.
The Washington think tank estimates Russia has suffered about 1.4 million casualties, including roughly 450,000 killed, while Ukraine has sustained between 525,000 and 625,000 casualties, including an estimated 125,000 to 150,000 deaths.
Officials cautioned that exact casualty figures remain difficult to verify because "Moscow is believed to routinely undercount its war dead and injured, and Ukraine does not disclose its official figures," according to the outlet.
The CSIS estimates rely on U.S. and British government intelligence assessments, among other sources.
The report says the conflict has produced enormous losses while yielding little movement on the battlefield.
Russian troops are advancing less than 165 feet per day in some sectors, and the study found that "Russia's territorial control in Ukraine shrank in the spring of 2026."
"Russian forces lost more ground than they captured in both April and May, a net loss of roughly 400 square kilometers and their first monthly net losses since August 2024, yet another sign of Russia's military struggles," the report said.
The increasingly static front has drawn comparisons among military analysts to the Battle of Verdun during World War I, where months of grinding combat produced only marginal territorial gains at an extraordinary human cost.
Military analysts say the war has become a grinding contest of artillery, drones, and fortified defensive positions, with both sides sustaining heavy casualties for limited territorial gains.
Russia still enjoys a significant manpower advantage, with military analysts estimating that more than 400,000 Russian troops face roughly 250,000 Ukrainian soldiers along the front lines.
Moscow has sustained its force levels through nationwide conscription, recruitment bonuses, prison enlistment programs and the deployment of more than 10,000 North Korean troops to help reclaim Russia's Kursk region.
Even so, CSIS estimates Russia's monthly casualty rate of 30,000 to 34,000 troops now likely exceeds its monthly recruitment rate of about 27,000 new soldiers.
The report also noted that Ukraine has become increasingly effective at taking the war inside Russia through long-range drones and missiles.
Last month, Kyiv launched its largest drone attack on Moscow since the war began, while this week Russia said it shot down 419 Ukrainian drones targeting the capital, Crimea, and other regions.
CSIS co-author Seth Jones said the mounting battlefield losses and expanding Ukrainian strikes are creating new pressures on the Kremlin.
"Russia is facing, by far, its darkest period of the war since its February 2022 invasion of Ukraine," Jones said.
"The war has come home to everyday Russians, who are paying the price of President [Vladimir] Putin's war with a sputtering economy, skyrocketing prices, a growing number of body bags coming back from the front lines and drone strikes in Russian cities."
The report comes as President Donald Trump has largely distanced the United States from the conflict.
Speaking at a summit in France last month, Trump said, "Look, we have nothing to do with it," adding that the war "has no impact on us, other than we sell weapons" to Ukraine.
CSIS concluded that without greater military and economic pressure from the United States and Europe, Putin is likely to continue prosecuting the war despite the mounting casualties and economic costs.