KYIV/POKROVSK, Ukraine—Russian forces have fully occupied Sievierodonetsk, the mayor of the eastern Ukrainian city said on Saturday, confirming Kyiv’s biggest battlefield setback for more than a month, after weeks of some of the war’s bloodiest fighting.
Ukraine called its retreat from the city a “tactical withdrawal” to fight from higher ground in Lysychansk on the opposite bank of the Siverskyi Donets river. Pro-Russian separatists said Moscow’s forces were now attacking Lysychansk.
