Since President Trump decided to pull U.S. troops from northern Syria, Russians have been moving into the territory abandoned by the Americans. On Thursday, Russian troops took over an air base that had been controlled by U.S. forces near Raqqa—the onetime capital of the Islamic State. The Russians, who are allies of Syrian President Bashar al-Assad, have also occupied former U.S. airbases in Qamishli and Tabqa in recent weeks. Trump announced in October that the U.S. was withdrawing from Syria ahead of a Turkish incursion into Kurdish areas.