Ukraine says it has ordered troops to withdraw from the key battleground city of Sievierodonetsk after weeks of fierce street fighting.
Officials said there is very little left to defend in the bombed-out eastern city, where hundreds of civilians reportedly remain trapped in a chemical plant.
The retreat, they said, is aimed at limiting more casualties and regroup, but the move will be seen by Russia as a significant victory.
South of Sievierodonetsk, Ukrainian soldiers also withdrew from the towns of Hirske and Zolote in the face of overwhelming Russian forces, an adviser to President Volodymyr Zelensky said.
The Pentagon sought to play down the importance of the retreat, emphasizing that the cost to Russia "for this very small, very incremental gain".
"What (the Ukrainian troops) are doing is putting themselves in a position where they can better defend themselves," AFP quoted an unnamed senior Pentagon official as saying.
The eastern industrial hub of Sievierodonetsk has been the scene of weeks of street battles as outgunned Ukrainians put up a stubborn defense, and as Russians aim to consolidate power throughout the Donbas.
But Serhiy Haiday, governor of the Lugansk region that includes Sievierodonetsk, said Friday that Ukrainian military forces in the city had received the order to withdraw.
The latest Russian advances appeared to bring Moscow closer to taking full control of Luhansk, one of President Vladimir Putin's objectives.
They set the stage for Lysychansk to become the next main focus. According to some estimates, Russia now controls some 20 percent of Ukrainian territory.
As the biggest land conflict in Europe since World War Two entered its fifth month, Russian missiles on Saturday rained down across Ukraine, hitting military facilities in the west and the north as well as a southern city.
Artillery and airstrikes also pounded the twin cities of Sievierodonetsk and Lysychansk.
"48 cruise missiles. At night. Throughout whole Ukraine," Ukrainian presidential adviser Mykhailo Podolyak said on Twitter. "Russia is still trying to intimidate Ukraine, cause panic and make people be afraid."
Vitaly Kiselev, an official in the Interior Ministry of the separatist Luhansk People's Republic told Russia's TASS news agency that it would take another week
and a half to secure full control of Lysychansk.
The governor of Lviv region in western Ukraine said six missiles were fired from the Black Sea at the Yavoriv base near the border with Poland. Four hit the target but two were destroyed.
Vitaliy Bunechko, governor of the Zhytomyr region in the north of the country, said the strikes on a military target killed at least one soldier.
"Nearly 30 missiles were launched at one military infrastructure facility very near to the city of Zhytomyr," said Bunechko, adding that nearly 10 missiles had been intercepted and destroyed.
In the south, the mayor of Mykolaiv near the Black Sea said five cruise missiles hit the city and nearby areas on Saturday.
Ukraine on Friday again pressed for more arms, with its top general, Valeriy Zaluzhniy, telling his US counterpart in a phone call that Kiev needed "fire parity" with Moscow to stabilize the situation in Luhansk.
The war has had a massive impact on the global economy and European security arrangements, driving up gas, oil and food prices.
The West has imposed an unprecedented package of sanctions on Russia, its top companies and its business and political elite.
British Prime Minister Boris Johnson said on Saturday that he feared Ukraine could face pressure to agree a peace deal with Russia.
Johnson said the consequences of Putin getting his way in Ukraine would be dangerous to international security and a long-term economic disaster.