DONETSK, November 21. /TASS/. During the battle for Kupyansk, the armed forces of Ukraine lost its most battle-seasoned troops, including elite drone teams and special forces, a source from a Russian security agency has told TASS.

‘The armed forces of Ukraine has lost its most battle-seasoned troops in Kupyansk, particularly elite drone operators and special forces," the source said. "It also sustained serious losses among the well-trained infantry."

The source said that the majority of losses occurred over the past month and a half, as Ukraine desperately tried to stabilize the situation in the city.