Russian forces are continuing their attacks on the eastern Ukrainian region of Donetsk but are reportedly suffering significant personnel and equipment losses.

The Ukrainian Air Force said on Friday that the Russian military mounted attacks overnight in the country's south and other areas using six Iranian-made drones. It also said Russia launched a short-range ballistic missile toward the Kharkiv region in the country's east. The Ukrainian force added that five of the six drones were destroyed.

Ukrainian Internal Affairs Minister Ihor Klymenko said on Friday that a missile hit and damaged a fire department building in the Kharkiv region's strategic city of Izyum, wounding eight officials.

Russian forces are continuing their efforts to capture the city of Avdiivka in the Donetsk region.

A US think tank, the Institute for the Study of War, said in its analysis on Thursday, "Heavy Russian equipment losses around Avdiivka will likely undermine Russian offensive capabilities over the long term."

The think tank also said satellite imagery has confirmed that the Russian military lost more than 100 tanks and other military vehicles near the city between October 10 and 20.

US National Security Council Coordinator John Kirby said on Thursday, "Russia's mobilized forces remain undertrained, underequipped and unprepared for combat."

He said, "Russia continues to show no regard for the lives of its soldiers," and "We have information that the Russian military has been actually executing soldiers who refuse to follow orders."