Ukraine said on Friday its forces may need to retreat from their last pocket of resistance in Luhansk to avoid being captured by Russian troops pressing an advance in the east that has shifted the momentum of the three-month-old war.

A withdrawal could bring Russian President Vladimir Putin closer to his goal of capturing Ukraine's Luhansk and Donetsk regions in full. His troops have gained ground in the two areas collectively known as the Donbas while blasting some towns to wastelands...