Russia says it has detected a shift from U.S. President-elect Donald Trump and his team towards recognising the "realities" on the ground in Ukraine, and sees this as a welcome sign as it prepares to study his plan for ending the war.

Russia welcomes signals coming from President-elect Donald Trump over the Ukraine conflict, less than a week before the Republican takes office.

Ukraine introduced emergency power cuts in six regions amid what authorities described as a "massive" Russian missile strike, the national grid operator said on Wednesday.

Ukraine struck Russian regions with a major drone and missile attack overnight, damaging at least two factories and forcing schools to close in a major southern Russian city, according to Russian officials and media.

Ukraine fired six British Storm Shadows and six US-made ATACMS ballistic missiles during its largest aerial bombardment of Russia in the war so far, Ukrainian and Russian officials have said.