Ukrainian President Volodymyr Zelensky has acknowledged, for the first time, that his military is conducting an offensive inside Russia's western Kursk region.
In his nightly televised address on Saturday, Mr Zelensky said Ukraine's military is pushing the war "onto the aggressor's territory."
This comes five days after Ukraine began its operation, which has taken Russia by surprise and prompted mass evacuations across both sides of the border.
In Ukraine, explosions were reported in the capital Kyiv and in the Sumy region in the early hours of Sunday.
Kyiv mayor Vitali Klitschko said air defence units are "operating" and air raid alerts continue in the city. Writing on the Telegram messaging app he warned civilians to stay in shelters.
