A U.S. F-16 downed a Turkish drone in northeast Syria after officials deemed it a threat to U.S. forces, The Wall Street Journal reported, citing a person familiar. Turkey, a NATO ally, has been carrying out air attacks on Kurdish militants. At the same time, around 900 members of the U.S. military have worked with fighters led by the Kurds in its efforts against the Islamic State. A U.S. official told the Journal that the U.S. knew it was a Turkish drone before firing upon it. The episode may raise tensions between the allied nations, with U.S. Secretary of Defense Lloyd Austin set to meet with Turkish officials, the Journal reported.