Ukraine's capital, Kyiv, began the new year under attack by Russian drones that caused severe power outages.

Ukrainian military officials say drones made in Iran attacked the city from Sunday night through early Monday. They say more than 40 drones were shot down using weapons supplied by Western countries.

Kyiv mayor Vitali Klitschko says the attacks damaged the city's electrical grid, and Kyiv has resorted to emergency blackouts to save power.

Meanwhile, Ukrainian forces are stepping up their offensive in the eastern region of Luhansk to recapture the city of Kreminna. Russian forces control the city and are using it as a supply base.