Western equipment has slotted in to Ukraine's embattled, Soviet-era military throughout the war, including long-range missiles and advanced fighter jets.

U.S. President Joe Biden said on Wednesday he had asked the Defense Department to continue its surge of weapons deliveries to Ukraine, after condemning Russia's Christmas Day attack on Ukraine's energy system and some of its cities.

Ukrainians faced fresh Russian drone and missile strikes on energy infrastructure nationwide on Tuesday night into Christmas Day morning.

Moscow again struck Ukraine’s energy infrastructure, part of an effort to wear down the country. “In the trenches, there are no holidays,” one man said.

Russia attacked Ukraine's energy system and some cities in an "inhuman" Christmas Day assault, Ukraine's President Volodymyr Zelenskyy said.

Russia launches a Christmas Day missile attack on Ukraine as the war enters its third year. NBC News’ Erin McLaughlin reports on the shifting battleground there and in Washington, D.C.

Russian troops appeared to have made inroads into Ukranian territory on Christmas Eve, as well as striking the city of Kharkiv.

Pope Francis has called for negotiations between Ukraine and Russia to end the war triggered by Russia's invasion of Ukraine in 2022. In his traditional Christmas Day address, the Pope said "boldness [was] needed to open the door" to dialogue "in order to achieve a just and lasting peace" between the two sides.

Zelensky warns of greater military cooperation between Moscow and Pyongyang, including sending more troops and military equipment

Back then, in the first weeks of the war, Russia and Ukraine conducted several rounds of talks in person and online aimed at ending the conflict; although a framework for peace called the Istanbul Communiqué was drawn up,

Ukrainian President Volodymyr Zelenskyy said more than 3,000 North Korean soldiers have been killed or wounded fighting for Moscow in Russia's western Kursk region.