(Bloomberg) -- A Ukrainian drone attack hit one of Russia’s biggest refineries in an assault President Vladimir Putin said was aimed at disrupting his presidential election later this week.Most Read from BloombergStock Traders Bracing for Worst Shrug Off Hot CPI: Markets WrapEx-Wall Street Banker Takes On AOC in New York Democratic PrimaryUnited Tells Boeing to Stop Making Its Long Delayed Max 10sChina Has Never Canceled This Many Shipments of US WheatTrump Wins Republican Nomination, Setting Up