Russia fired two dozen combat drones at Ukraine early on Thursday, striking a university campus in the Black Sea city of Odesa and attacking the capital Kyiv for the third time in four days.
Russia has stepped up attacks as Ukraine prepares for a counteroffensive to try to retake Russian-occupied land in the south and east. Russian shelling in the frontline southern region of Kherson killed at least 23 civilians on Wednesday.
Air Force Colonel Yuriy Ihnat said Russia's military was using "kamikaze" drones, which fly towards their target before blowing up, to weaken Ukrainian air defences.
