Ukraine has vowed to strengthen its armed forces after Russia launched its biggest aerial assaults on cities since the beginning of the war, forcing thousands to flee to bomb shelters and prompting Kyiv to halt electricity exports to Europe.

Missiles hit targets across Ukraine on Monday morning, killing 14 people and injuring scores, as they tore into intersections, parks and tourist sites.

Explosions were reported in Kyiv, Lviv, Ternopil and Zhytomyr in western Ukraine, Dnipro and Kremenchuk in the center, Zaporizhzhia in the south and Kharkiv in the east, Ukrainian officials said.