As Russian missile strikes and heavy assaults by ground troops pace deadly attacks on Ukraine, a new report by University of Virginia researchers reveals another destructive facet of Russia’s invasion.

Using commercial satellite imagery and other open-source information, associate professor of sociology Fiona Greenland and other researchers with UVA’s Cultural Resilience Informatics and Analysis, or CURIA, Lab determined that multiple ancient Ukrainian burial mounds have been damaged in two locations currently occupied by Russian troops—a potential violation of international law.

These historically significant burial sites, called “kurgans,” were constructed by the ancient peoples of the Ukrainian steppe. The mounds, up to 65 feet tall, contain human remains and artifacts dating back as far as 3000 B.C.E.