Russian shells crashed down on power infrastructure in Kherson again on Thursday, knocking out electrical service that had only recently been restored to the southern city’s beleaguered residents.
The bombardment in Kherson was the latest setback for the city, which Ukrainian forces only liberated on Nov. 11. Russian troops withdrew east across the Dnipro River and have since then fired hundreds of shells at the city from their new positions.
The strike was the latest example of a widespread problem facing Ukraine, where some six million people were without power on Thursday: As crews race to restore basic utilities to a country facing a long winter and rolling blackouts, new Russian attacks threaten to undo their work .
Almost since Ukraine recaptured Kherson after months of occupation, authorities have urged vulnerable residents to leave the city because of the lack of power and water, even as they rushed to reconnect supplies for those who will remain.
On Wednesday, the authorities said they had restored power to 20 percent of customers in the city — only to have more strikes cause fresh outages a day later.
“There is no voltage in power lines in Kherson,” Yaroslav Yanushevych, the head of the regional military administration, said in a post on the Telegram social messaging app. “This happened because of large-scale attacks on the city by the Russian invaders.”
In Moscow, Sergei V. Lavrov, Russia’s foreign minister, repeated the Kremlin’s line that Ukraine’s power grid a legitimate military target. The United Nations has said that such attacks, which have left civilians without power as winter arrives, could amount to a war crime.
Russian forces fired 34 shells on Thursday that hit five settlements in the broader region, killing one person and wounding two others, Mr. Yanushevych said, adding that engineers from local power company Khersonoblenergo were again working to restore power lines.
Russia’s aerial attacks on Ukraine’s energy infrastructure escalated sharply in October as Moscow sustained a series of battlefield losses that military experts say thwarted its push to capture Ukraine’s entire Black Sea coast and the whole of the eastern Donbas region.
Ukrainian officials warned there was no indication the attacks would stop.
“There is still a threat of missile strikes on critical infrastructure of Ukraine and military facilities in the near future,” Brig. Gen. Oleksii Hromov, a member of Ukraine’s General Staff, warned on Thursday. “The enemy’s goal is to cause panic in the population.”
Soon after he spoke, air raid alarms sounded across the country, though they were followed by an all-clear.
The European Union and the United States have started to deliver both transformers and heavy generators. Still, it will take six months to restore the damaged infrastructure, according to Andriy Herus, head of Ukraine’s committee on energy and housing.
For now, Ukraine has instituted a series of rolling blackouts to try to conserve what energy it has. A total of 520 cities, towns and villages were facing power supply problems this week because of the attacks, an internal affairs ministry official said.
“During this winter it is impossible to restore all the damaged facilities of the energy infrastructure,” Mr. Herus said on Ukraine’s Espresso television channel. “The Ukrainian energy system is under constant Russian fire.”
Places on the conflict’s front lines, including the city of Kherson, face a particular problem because they are also subject to local mortar and artillery fire as well as missile and drone strikes.
In Donetsk, a province in Donbas where fighting remains intense, the head of the regional military administration told journalists on Wednesday that it was too dangerous for engineers to try to fix the power system in Bakhmut, a city that has been devastated over months of Russian attempts to capture it.
“Aerial power lines are destroyed to the extent that we can count them in kilometers,” the official, Pavlo Kyrylenko, said. He added that 1,235 people had been killed by shelling in the province since February.