The Washington-based Center for Strategic and International Studies (CSIS) has released an analysis estimating that total military casualties in the Russia-Ukraine war have surpassed two million since February 2022. The study calculates that Russian forces have suffered approximately 1.4 million casualties, including 400,000 to 450,000 killed, while Ukrainian forces have sustained between 525,000 and 625,000 casualties, with 125,000 to 150,000 fatalities. These figures, drawn from US and UK government estimates among other sources, mark the highest losses for a major power since the Second World War.

The data also show a sharp deceleration in Russian territorial gains. According to the study, Russian forces seized or infiltrated just 40.64 square kilometres between December 2025 and May 2026, compared with 515.84 square kilometres in the same period a year earlier. In April and May 2026, Russia suffered a net loss of approximately 400 square kilometres, its first monthly territorial losses since August 2024. Analysts in Washington attribute this shift to Ukraine’s expanded medium-range drone campaign, improved defensive tactics including frequent local counterattacks, and a battlefield saturated with drones and dense minefields that has created a danger zone more than 20 kilometres wide, limiting advances to between 50 and 90 metres per day on major fronts.

The study highlights a growing manpower imbalance. Russian monthly casualties are estimated at 30,000 to 34,000, while recruitment has fallen to around 27,000 per month, meaning losses now outpace the Kremlin’s ability to replace them. The casualty ratio has reportedly widened to nearly eight Russian casualties for every one Ukrainian in the first half of 2026, up from two or three to one earlier in the war. Viewed from Kyiv, the effectiveness of deep-defence strategies and drone warfare has been central to inflicting disproportionate losses on Russian forces, while Moscow has relied on forced conscription, recruitment of prisoners, and the deployment of North Korean troops to sustain its front-line numbers.

The study’s release comes as the conflict enters its fifth year with no diplomatic resolution in sight. The United States, under President Donald Trump, has signalled a reduced engagement, stating the war does not directly affect American interests beyond arms sales. European allies, meanwhile, continue to assess the implications of the attritional balance for their own security. The CSIS analysis is expected to inform ongoing debates in Western capitals about the sustainability of Russian operations and the future of military support for Ukraine.