"Ukraine was brutally attacked on Christmas Day," said Keith Kellogg, President-elect Donald Trump's pick for Ukraine and Russia envoy.

Russia launched aerial attacks on Ukraine’s energy sector “on a massive scale” overnight into Wednesday, local authorities said, with explosions reported across the country amid intensified bombardments that have left Ukraine in a precarious position while the war grinds into a third winter.

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

Police and media reports say that Finnish authorities have detained a Russia-linked ship as they investigate whether it damaged a Baltic Sea power cable and several data cables.

Finland’s leaders called for more NATO protection against alleged Russian sabotage on critical infrastructure.

Finnish authorities are investigating an oil tanker that is part of Russia’s shadow fleet over whether it cut an electricity cable between Finland and Estonia. The Eagle S was stopped by Finnish authorities after the Estlink 2 subsea electricity cable in the Gulf of Finland was disconnected on Wednesday.