Ukrainian drones targeted a Russian oil refinery hundreds of kilometers from the Ukrainian border, the latest in a campaign of deep strikes aimed at disrupting Russia’s oil industry. The May 31 overnight attacks on the facility in the central Saratov region -- the second since March -- did not appear to have caused any casualties. But a large fire and thick black smoke were reported at the plant belonging to the state-owned oil company Rosneft. Ukraine’s military said its drones targeted the Saratov refinery, along with several other…