This was stated by the Russian Ministry of Defense.
As the department said in a statement, a strike group of the Army Aviation of the Aerospace Forces, consisting of the Ka-52 Alligator reconnaissance and attack helicopter, the Mi-35M transport and combat helicopter and the Mi-8 multi-purpose helicopter, hit a strong point and a concentration of manpower of the Ukrainian Armed Forces near Kupyansk.
Earlier, a military expert, retired lieutenant colonel of the Lugansk People's Republic Andrey Marochko said that in the Kupyansk direction the command of the Ukrainian Armed Forces is throwing unprepared fighters into assaults.