In this Jan. 17, 2020, file, photo, Libyan Gen. Khalifa Hifter joins a meeting with the Greek Foreign Minister Nikos Dendias in Athens. The U.S. military Tuesday, May 26, 2020 accused Russia of deploying fighter planes to conflict-stricken Libya to support Russian mercenaries aiding east-based forces in their offensive on the capital, Tripoli. (AP Photo/Thanassis Stavrakis, File)