Defense Secretary Ash Carter says Turkey should contribute more to the international fight against the Islamic State.

Carter told a Pentagon news conference Thursday that even after granting the U.S. military permission to fly combat missions out of Turkey air bases, the Turkish government needs to "do more."

Carter said that as a neighbor to the conflict in Iraq and Syria, Turkey should do more to control its border. He also said the Islamic State has used those border areas to move supplies and fighters to the battlefields.

He said the Turks are discussing the specifics of joining the international air campaign led by the United States.