Ukrainian forces begin withdrawing from eastern city of Sievierodonetsk after intense combat, officials say

After weeks of ferocious fighting, Ukrainian forces have begun retreating from a besieged city in the country's east to move to stronger positions, a regional official said Friday, the four-month mark in Russia's invasion.

The planned withdrawal from Sievierodonetsk, the administrative center of the Luhansk region, comes after relentless Russian bombardment that has reduced most of the industrial city to rubble and cut its population from 100,0000 to 10,000. Ukrainian troops fought the Russians in house-to-house battles before retreating to the huge Azot chemical factory on the city's edge, where they remain holed up in its sprawling underground structures in which about 500 civilians also found refuge.

In recent days, Russian forces have made gains around Sievierodonetsk and the neighboring city of Lysychansk, on a steep bank across a river, in a bid to encircle Ukrainian forces.