Syria war: Who are Russia's shadowy Wagner mercenaries?

Syria war: Who are Russia's shadowy Wagner mercenaries?  BBC News Russia's anti-US aggression takes a deadly turn  CNBC 'A Total F***-up': Russian Mercenaries in Syria Lament US Strike That Killed Dozens  Newsweek Putin ally said to be in touch with Kremlin, Assad before his mercenaries attacked US troops  Washington Post The Kremlin's Parallel State Is a Feature, Not a Bug (Op-ed)  The Moscow TimesFull coverage