Russian troops have resumed the shelling of the southern Ukrainian city of Kherson, cutting the electricity supply to the recently liberated city, as fierce fighting continues in the east and officials cautioned that Ukraine faces a tough winter because of the Russian missile attacks on its infrastructure.

“Russian invaders shelled Kherson — damaged power grids. The city was left without electricity again,” Governor Yaroslav Yanushevych said on Telegram, adding that technicians were already at work trying to repair the damage and restore power to the recently liberated city located on the right bank of the Dnieper River.

Kherson was returned to Ukrainian control on November 11, as the Russian military retreated to the left bank of the Dnieper. Russian artillery took new positions across the river and has been regularly pounding the city with artillery and rockets.

Three people were killed the previous day in the city by Russian shelling, Yanushevych said.

Millions of Ukrainians are struggling without electricity and heating at the onset of winter following waves of Russian strikes across the country, and Russian President Vladimir Putin said on December 2 that further attacks on Ukraine’s infrastructure were “inevitable.”

Ukrainian officials have responded with defiance, vowing to do everything to contain the damage.

Maksym Tymchenko, chief executive officer of DTEK, a major power company, said on December 2 that all six of DTEK’s power stations had been attacked, some of them several times. The company has managed to bring them all back to the grid, he said.

Tymchenko voiced confidence that there was no chance “for the Russians to plunge Ukraine into darkness.”

Yet, there was a power-generation deficit and issues with electricity transmission, Tymchenko told the Kyiv Security Forum.

He said that in Kyiv, the company was trying to introduce “rolling controlled blackouts: three-four hours of electricity supply, followed by four hours break. This situation will continue, we hope, until next week only, if there are no further attacks. But we are prepared for further attacks.”

Additionally, he said, “We managed to accumulate enough coal stock for the country, not just for our company. We have enough gas storage to use gas for power generation. So we have enough capacity for the whole country.”

“Transformers, substations, high-voltage transformers: these are what we’ve been in deficit of, and what we appeal to our international partners for. Some of the equipment is already on the way to Ukraine,” he said.

Mayor Vitali Klitschko told the forum that last week Kyiv had faced an almost total blackout. “There was no heat and water supply. And about 4,000 employees of utility companies worked day and night to restore them.”

Defense Minister Oleksiy Reznikov told the forum that the months ahead would be difficult.

“The enemy still has significant resources, but there are more and more signs that he needs a pause at any cost,” he said.

As fierce fighting continues in the east, where Kyiv’s forces fought off waves of attacks in Luhansk and Donetsk regions, the military reported on December 3 that over the previous day it shot down an enemy helicopter and six drones.

The General Staff said in its regular update that Russian forces launched five missile strikes, 27 air strikes, and 44 rocket attacks at civilian infrastructure and Ukrainian Army positions along the contact line.

Meanwhile, Britain’s Defense Ministry said in its daily intelligence update that Russia is likely planning to encircle Bakhmut in the Donetsk region with tactical advances to the north and south.

Although the capture of Bakhmut would have limited operational value, it could allow Russia to threaten Kramatorsk and Slovyansk, the ministry said on December 3. “There is a realistic possibility that Bakhmut’s capture has become primarily a symbolic, political objective for Russia,” it said on Twitter.

The battlefield reports could not be independently verified.

With reporting by Reuters and CNN