Russian troops struck Kharkiv for the second time on 28 December, mayor Ihor Terekhov has said.
"One of the infrastructure facilities was targeted," he noted.
He suggested it was likely hit by an Iranian-made Shahed drone.
On the morning of 28 December, the Russian army fired S-300 missiles on the city's Slobidskyy district, having wounded one person. The attack did not affect the energy system.