Volleys of Russian missiles struck a series of Ukrainian regions early on Thursday, including the Black Sea port of Odesa and the second city of Kharkiv, knocking out power to several areas, regional officials said.
The governor of Odesa region, Maksym Marchenko, said on Telegram that a mass missile attack had hit an energy facility in the port city, cutting power. Residential areas had also been hit, but no casualties were reported.
Kharkiv region Governor Oleh Synehubov said the city and region had been hit by 15 strikes, with targets including infrastructure. Other strikes were reported in the central city of Dnipro and regions throughout the country.
Late on Wednesday, Ukraine's military said it had managed to push back intense Russian attacks on the city of Bakhmut despite a Russian claim of control over its eastern half.
As one of the bloodiest battles of the year-long war ground on in the small city's ruins, Ukrainian defenders – who last week appeared to be preparing for a tactical retreat – remained defiant.
"The enemy continued its attacks and has shown no sign of a letup in storming the city of Bakhmut," the general staff of the Ukrainian armed forces said on Facebook. "Our defenders repelled attacks on Bakhmut and on surrounding communities."
Ukrainian military and political leaders now speak of hanging on to positions and inflicting as many casualties as possible on the Russians to grind down their fighting capability.
President Volodymyr Zelensky said in late Wednesday video address that the battle for Bakhmut and the surrounding Donbas region was "our first priority".
In a separate interview with CNN, he said: "We think that in the Donbas direction Russia has started its offensive. This is the offensive. This is what it looks like: a slow aggression, because they don't have enough strength and forces."
Yevgeny Prigozhin, head of the Russian mercenary group Wagner, said his fighters had captured the eastern part of Bakhmut. If true, Russian forces would control nearly half the city in a costly pursuit of their first big victory in several months.
"Everything east of the Bakhmutka River is completely under the control of Wagner," Prigozhin said on the Telegram messaging app.
The river bisects Bakhmut, on the edge of Ukraine's Donetsk province that is already largely under Russian occupation. The city centre is on the west side of the river.
Prigozhin has issued premature success claims before. Reuters was not able to verify the situation on the ground.
Ukrainian military analyst Oleh Zhdanov said that in addition to the Zabakhmutka district on the eastern outskirts of Bakhmut, the Russians had captured Ilyinivka district on the north side.
"The situation is critical," he said in a video commentary, adding that Russian forces had also made gains near Avdiivka to the south of Bakhmut as well as to the north around Svatovo.