Ukrainian troops said they had taken the key bastion of Lyman in occupied eastern Ukraine, a stinging defeat that prompted a close ally of Russian President Vladimir Putin to call for the possible use of low-grade nuclear weapons. 

The capture on Saturday came just a day after Putin proclaimed the annexation of nearly a fifth of Ukraine – including Donetsk, where Lyman is located – and placed the regions under Russia’s nuclear umbrella. Ukrainian soldiers announced the capture in a video recorded outside the town council building in the centre of Lyman and posted on social media by Kyrylo Tymoshenko, deputy head of President Volodymyr Zelensky’s office. “Dear Ukrainians - today the armed forces of Ukraine ... liberated and took control of the settlement of Lyman, Donetsk region,” one of the soldiers says.