The grinding war pitting Ukraine against its Russian invaders has escalated ahead of Donald Trump’s inauguration.

U.S. leaders from President Joe Biden on down are being careful not to declare a premature victory after a Ukrainian offensive forced Russian troops into a messy retreat in the north.

Russia has unleashed a string of attacks against rail and fuel facilities deep inside Ukraine in an apparent attempt to thwart Ukrainian efforts to marshal supplies.

Russia’s failure thus far to win complete control of Ukrainian airspace has been a surprise, given Russian military strength and the importance of dominating the skies.