A Ukrainian drone strike has knocked the Lukoil-operated Volgograd refinery offline, halting one of Russia’s largest fuel processing hubs as Ukraine continues with its campaign to take advantage of Moscow’s downstream vulnerability to long-range attacks. The Thursday attack, confirmed by regional authorities and company sources, ignited fires in the refinery’s main crude distillation unit and hydrocracker, forcing a full suspension of operations pending assessment, according to Reuters. The CDU-5 unit, which handles…