Newly confirmed Secretary of State Mike Pompeo confirmed two weeks ago that the US killed hundreds of Russians during a large firefight in Syria in early February.
"In Syria now, a handful of weeks ago, the Russians met their match," Pompeo said. "A couple hundred Russians were killed."
The Russians were part of Wagner Group, or Vagner Group, a private mercenary company reportedly contracted by the Syrian government to capture and secure oil and gas fields from ISIS.
The Wagner Group started getting attention in 2014 when its mercenaries fought alongside Russian-backed separatists in Ukraine, before moving to Syria.
While little is still known about the shadowy mercenary group, they are believed to be operating in at least the following three countries: