“In February, U.S. strikes reportedly killed a large number of Russians working for Wagner Group, a private military company owned by a crony of Russian President Vladimir Putin, after the Russians crossed the Euphrates River deconfliction line and tried to capture a refinery and nearby oil and gas fields by the Syrian city of Deir Ezzor. After the Russians came in contact with U.S. forces at the site, the Americans responded with aircraft and artillery, killing and wounding up to 300 Russians. Why was Wagner Group there? Because the Russians may have drawn the wrong lessons from the U.S. use of contractors in Iraq and Afghanistan.”
Source: Russia’s Use of Armed Contractors in Syria Gives the U.S. Leverage | RealClearDefense