(Reuters) – The “Battle of Donbas” remains Russia’s main strategic focus in order to achieve its stated aim of securing control over the Donetsk and Luhansk regions, Britain’s defence ministry said on Friday. “In these oblasts fighting has been particularly heavy around Lysychansk and Severodonetsk, with an attempted advance south from Izium towards Slovyansk,” the ministry said on Twitter. Due to strong Ukrainian resistance, Russian territorial gains have been limited and achieved at significant cost to Russian forces, the ministry added in the regular bulletin. Reuters could not immediately …