Ukraine says Russian advances could force retreat in part of east

Ukrainian forces may have to retreat from their last pocket in the Luhansk region to avoid being captured, a Ukrainian official said, as Russian troops press 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 eastern 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.

Luhansk's governor, Serhiy Gaidai, said Russian troops had entered Sievierodonetsk, the largest Donbas city still held by Ukraine, after trying