Russia has suffered 100,000 casualties since December, a top White House official said, citing US intelligence.
John Kirby revealed that 20,000 Russian troops have been killed fighting in Ukraine in that time.
Ukrainian troops have fought the Russians along a largely static front line across eastern and parts of southern Ukraine for months.
In January 2023, the top general went on to say that Russia had suffered "significantly well over" 100,000 casualties.
Recently leaked US intelligence documents reviewed by Insider suggested that Russia had endured up to 223,000 casualties, including 43,000 soldiers killed in fighting.