The Yale University research lab was tracking thousands of Ukrainian children forcibly deported to Russia since the invasion began.

Observers fear the move has compromised evidence of war crimes by Russian officials and will hinder efforts to rescue thousands of missing Ukrainian children.

The U.S. State Department on Wednesday denied that data collected in a government-funded program that helps track thousands of abducted Ukrainian children had been deleted, but acknowledged that the effort had been terminated as part of Washington's sweeping freeze on almost all foreign aid.