Ukraine's grid has been battered countrywide since early October by targeted Russian strikes, in what U.S. officials call a Russian campaign to weaponize the coming winter cold.

Ahead of the meeting, NATO Secretary-General Jens Stoltenberg also said that Russian President Vladimir Putin "is trying to use winter as a weapon of war against Ukraine" and that NATO's allies and Ukraine "need to be prepared for more attacks."

The meeting in the capital Bucharest is likely to see NATO make fresh pledges of nonlethal support to Ukraine: fuel, generators, medical supplies, winter equipment and drone-jamming devices. Blinken will announce substantial U.S. aid for Ukraine's energy grid, U.S. officials said

Individual allies are also likely to announce fresh supplies of military equipment for Ukraine, chiefly the air defense systems that Kyiv so desperately seeks to protect its skies, but NATO, as an organization, will not, to avoid being dragged into a wider war with nuclear-armed Russia.

The ministers, along with their Ukrainian counterpart Dmytro Kuleba, will also look further afield.

"Over the longer term we will help Ukraine transition from Soviet-era equipment to modern NATO standards, doctrine and training," Stoltenberg said on Friday.