Ukrainian soldiers reportedly advanced over 15 kilometers underground, penetrating enemy rear lines in the Kharkiv region as part of Operation "Veles." The 2nd Assault Brigade of the National Guard of Ukraine "Kharтия" provided details of the operation.

The source claims that while tunnels have historically been used for defense, hiding, or localized sabotage, the Russian army under Avdiivka used underground routes for infantry infiltrations. Operation "Veles" is described as the first full-scale underground counteroffensive maneuver in world history.