A regional governor in eastern Ukraine said that the country's troops will retreat from a besieged city to avoid encirclement.

The city of Sievierodonetsk, the administrative center of the Luhansk region, has faced relentless Russian bombardment. Ukrainian troops fought the Russians in house-to-house battles before retreating to a huge chemical factory on the city’s edge, where they holed up in its sprawling underground structures.

Luhansk Gov. Serhiy Haidai said that the Ukrainian troops have now been given the order to leave Sievierodonetsk. Haidai said the Ukrainian forces have “received the order to retreat to new positions and continue fighting there” but didn’t give further details.

The city of nearly 100,000 has been the site of numerous battles since 2014.