Russia has sent tens of thousands of Ukrainian children, whom they have abducted, to more than 200 different facilities, where about a fifth of them have been given military training, according to a new report from a United States watchdog organization.

It’s believed that Russian forces have taken more than 35,000 Ukrainian children from their homes, largely in areas of Ukraine that Russia occupies, though the exact amount is unknown given the lack of information available in many of these areas, Nathaniel Raymond, the executive director of the Yale Humanitarian Research Lab, told the Washington Examiner.