Russian forces are trying to block a city in eastern Ukraine, the region’s governor said Saturday, after their relentless assault on a nearby city forced Ukrainian troops to begin withdrawal after weeks of intense fighting.

Russia also launched missile attacks on areas far from the heart of the eastern battles.

Serhiy Haidai, governor of the Luhansk region, said on Facebook that Russian forces are attempting to blockade the city of Lysychansk from the south. That city lies next to Sievierodonetsk, which has endured relentless assault and house-to-house fighting for weeks.

After Haidai said Friday that Ukrainian forces had begun retreating from Sievierodonetsk, military analyst Oleg Zhdanov said some of the troops were heading for Lysychansk. But Russian moves to cut off Lysychansk will give those retreating troops little respite.

Russian bombardment has reduced most of Sievierodonetsk to rubble and cut its population from 100,0000 to 10,000. Some Ukrainian troops are holed up in the huge Azot chemical factory on the city’s edge, along with about 500 civilians.