Secretary of State Antony Blinken will announce new aid Tuesday for Ukraine to rebuild its energy system damaged by Russian missile strikes, a senior State Department official said.

Blinken arrived in Romania Monday night before meeting with NATO allies and G7 foreign ministers. Ukraine's foreign minister told some NATO diplomats visiting Kyiv earlier in the day that the transformers were the most important element of the country's energy infrastructure that needed to be rebuilt.

A State Department spokesman, who spoke to reporters on condition of anonymity, said Washington is working with U.S. utility and equipment providers as well as European countries to find equipment to help Ukraine rebuild high-voltage transmission stations damaged by Russian missile strikes.

On Tuesday, during a meeting of the new energy coordination group, which includes members of the G7 and other countries, Blinken will announce plans to get energy equipment to Ukraine as soon as possible, the source said, adding that the transfer will happen probably in the next few weeks.

The source did not specify what form the aid would take or how much it would cost.

Washington is also urging other countries to do the same so Kyiv can prevent power outages that leave millions of people in the dark and without heating in sub-zero temperatures, the State Department source added.

Moscow is trying to deprive Ukrainians of power by hitting substations, the source said, adding that the million-dollar stations are vulnerable to Iranian war drones used by Russia in Ukraine.

Ukrainian Foreign Minister Dmytro Kuleba told a gathering of Northern European and Baltic foreign ministers that his country needs transformers and an improved air defense system.

Kyiv says the Russian attacks are aimed at harming civilians, making them war crimes. Moscow denies that its intentions include harming civilians, but said last week that civilian suffering will not end unless Ukraine gives in to Russia's demands. Zelenskiy called Moscow's destruction in Ukraine an act of revenge and promised that Ukraine will rebuild every object destroyed by the occupiers.

Snow has fallen in Kyiv and temperatures are hovering around zero, while millions of people in and around the Ukrainian capital are struggling with power and central heating outages as a result of Russian air strikes.

DTEK, Ukraine's largest private power producer, said it would cut power supplies to its customers in Kyiv by 60 percent.

National grid operator Ukrenergo said Monday that it had been forced to resume regular emergency power outages across the country after a failure to repair energy infrastructure.