As the Pentagon prepares to send the president a plan next week to speed the defeat of Islamic State in Iraq and Syria, a top U.S. commander has indicated the more robust effort will require additional U.S. troops, especially in Syria.

Gen. Joseph Votel, head of U.S. Central Command, has told reporters traveling with him in the region that in Syria, where a loose coalition of Kurds and Arabs are slowly moving on the Islamic State stronghold of Raqqa, the U.S. may have to “take on a larger burden,” according to reports by CBS and the New York Times.