This report maps a system of filtration facilities and processes employed by Russia and Russia-aligned forces to screen Ukrainian civilians, combatants (including potential prisoners of war), and other people present in Donetsk oblast beginning in March 2022. “Filtration” is defined within the context of this report as the multi-step system Russia and its proxies have deployed in territory they currently occupy within Ukraine to register, interrogate, and, in some cases, indefinitely detain people residing there at the time Russia and its aligned forces took that locale under its control.

There is evidence that the system was created weeks before the invasion began and likely grew following Russia’s capture of Mariupol in April 2022 to accommodate filtration of all citizens. Combining open source information with remote sensing data, the Yale Humanitarian Research Lab (Yale HRL) is able to present the most comprehensive public assessment to date of this large scale apparatus of screening and extrajudicial detention. Findings in this report are consistent with and expand on conclusions reached by other organizations and governmental bodies, including the United States National Intelligence Council.

While the total number of people who have passed through filtration cannot be reliably estimated, by 14 June 2022 the total number of civilians who had reached Russia from Ukraine rose to at least 1,700,000, including 276,000 children, according to the former Ukrainian Ombudswoman for Human Rights. On August 16, a Russian government representative reported figures twice as large – over 3,400,000 people, including over 550,000 children. It is unknown how many people are currently held within the filtration system.

The total number of facilities engaged in filtration operations in Donetsk oblast cannot be conclusively determined by open source analysis and remote sensing alone. Ground investigations are required to cross-corroborate these initial findings. However, Yale HRL has identified with high confidence at least 21 distinct locations in and around Donetsk oblast containing one or more facilities in the filtration system for civilians that Russia and its aligned forces have operated since the invasion.

Russia’s apparent filtration system for persons within Donetsk oblast, which includes use of extrajudicial and incommunicado detention, violates multiple elements of international humanitarian law and raises multiple potentially grave human rights issues.