U.S. officials say Syrian rebels fighting against ISIS were bombed by Russian planes.
U.S. Army Lt. Gen. Stephen Townsend, who leads the anti-ISIS coalition, said the bombing appears to have been an accident. Townsend also said some Syrian fighters were killed, but he didn't give a specific number.
He told the New York Times, "We had some Russian aircraft and regime aircraft bomb some villages that I believe they thought were held by ISIS."
Russia says the bombing never happened. A Russian Defense Ministry statement said, "No airstrikes were carried out by either Syrian or Russian aircraft in areas designated by the U.S. side."
But in February, Russia did admit to accidentally bombing Turkish soldiers in Syria. Russia's Vladimir Putin apologized to Turkey's president, Recep Tayyip Erdogan, after three soldiers were killed.