President Volodymyr Zelensky of Ukraine is warning that Russia is planning more mass strikes on its energy infrastructure as officials over the weekend urged civilians to stock up on essentials and brace for a cold winter. Frustrated and facing battlefield setbacks, Russia has turned with increasing fury on civilians, seeking to undermine Ukraine’s morale by pummeling power stations and other basic infrastructure with drone and missile attacks.

“We also understand that the terrorist state is concentrating forces and means for a possible repetition of mass attacks on our infrastructure. First of all, energy,” Mr. Zelensky said in his nightly address.

Russia has already damaged or destroyed 40 percent of Ukraine’s power grid and officials have imposed rolling blackouts to keep it from failing.

Ukrainian officials said that the destruction of infrastructure in towns and cities near the front and in recently liberated areas could lead to half a million newly displaced people seeking refuge in other parts of the country.

“Over the past three months, 135,000 people have moved from the areas where hostilities are taking place,” said Iryna Vereshchuk, a deputy prime minister in charge of the reintegration of formerly occupied territories. “At least 400 thousand may move during the winter period.”

The Ukrainian government has urged those who have fled the country to not return during the difficult winter months so as not to put further burden on battered infrastructure.
Mr. Zelensky said Sunday night that more than 4.5 million Ukrainians were already without electricity due to controlled rolling blackouts, with the majority in the capital, Kyiv, and the Kyiv region.

Mr. Zelensky’s remarks came after both Russian and Ukrainian officials said that the city of Kherson, where both sides seem to be bracing for battle, and 10 surrounding settlements were without power after a high-voltage power line was blown up.

He said that Ukraine expects Russia to carry out more attacks using Iranian-made drones — which have been launched to deadly effect in recent strikes across the country — and met with officials and energy companies about “probable scenarios” in the energy sector. Although Ukraine has gotten better at shooting down the attack drones, the small percentage that get through have still caused extensive damage and energy companies have cited the immense challenge of racing to repair damaged facilities as equipment runs low the threat of further strikes persists.

Vitali Klitschko, the mayor of Kyiv, warned residents of the capital over the weekend to prepare for the worst.

“Let’s be frank, our enemies are doing everything for the city to be without heat, without electricity, without water supply, in general, so we all die,” he told Ukrainian news outlets. “The future of the country and the future of each of us depends on how prepared we are.”

In a statement posted on the Telegram messaging app on Sunday, Mr. Klitschko urged Ukrainians to conserve electricity and said that the city has purchased backup generators and heating systems from foreign partners as part of contingency planning.

Roman Tkachuk, the director of security in Kyiv, said in an interview on Friday that the government was preparing for a cold winter and had an emergency plan should the city lose electricity completely, but emphasized that the situation, while difficult, was currently under control.