Ukraine on Sunday claimed full control of the eastern logistics hub of Lyman, its most significant battlefield gain from Russia in weeks, Reuters reported.
The setback for Russian President Vladimir Putin came two days after he proclaimed the annexation of four regions covering nearly a fifth of Ukraine, an area that includes Lyman.
NATO Secretary General Jens Stoltenberg said the capture of the town, where Ukrainian flags were raised over civic buildings on Saturday, demonstrated that Ukraine is capable of dislodging Russian forces and showed the impact Ukraine's deployment of advanced Western weapons was having on the conflict.
Ukrainian President Volodymyr Zelenskyy said on Sunday that the success of the country's soldiers was not limited to the recapture of Lyman, claiming Ukrainian forces have liberated the small Arkhanhelske and Myrolyubivka settlements in the Kherson region as well.
Reuters was not able to immediately verify the reports.
Russia's defense ministry said on Saturday that it was pulling troops out of the Lyman area "in connection with the creation of a threat of encirclement".
It did not mention Lyman in its daily update on fighting in Ukraine on Sunday, although it said Russian forces had destroyed seven artillery and missile depots in the Ukrainian regions of Kharkiv, Zaporizhzhia, Mykolaiv and Donetsk.
Russian forces had initially captured Lyman from Ukraine in May and had been using it as a logistics and transport hub for its operations in the north of the Donetsk region. Its recapture by Ukrainian troops is Russia's largest battlefield loss since Ukraine's counteroffensive in the northeastern Kharkiv region in September.
The areas Putin claimed as annexed just over seven months into Russia's invasion of Ukraine, Donetsk and Luhansk plus Kherson and Zaporizhzhia in the south, are equal to about 18% of Ukraine's total surface land area.
The annexation has been condemned by the United States, which announced a new round of sanctions against Russia following the move, and by NATO, which said, "This land grab is illegal and illegitimate."
Israel's Foreign Ministry announced on Tuesday that Israel would not recognize the results of referendums held in Russian-occupied parts of Ukraine.
“Israel recognizes the sovereignty and territorial integrity of Ukraine and will not recognize the results of referendums in the eastern districts of Ukraine,” the Foreign Ministry said.