Ukrainian troops said on Saturday they had taken the key bastion of Lyman in occupied eastern Ukraine, a stinging defeat that prompted a close ally of President Vladimir Putin to call for the possible use of low-grade nuclear weapons.
The capture came just a day after Putin proclaimed the annexation of four Ukrainian regions - including Donetsk, where Lyman is located - and placed them under Russia's nuclear umbrella, at a ceremony that was condemned by Kyiv and the West as an illegitimate farce.
