The capital of Kyiv was hit on Monday by kamikaze drones, Andriy Yermak, head of the Ukrainian president's staff, wrote on the Telegram messaging app.
"Russians think it will help them," Yermak said.
Reuters was not able to independently verify the claims.
(Reporting in Kyiv by Pavel Polityuk; Writing in Melbourne by Lidia Kelly; Editing by Tom Hogue)