WASHINGTON — The Obama administration has not ruled out establishing a no-fly zone over northeastern Syria to protect civilians from airstrikes by the Syrian government, Defense Secretary Chuck Hagel and Gen. Martin E. Dempsey, the chairman of the Joint Chiefs of Staff, said Friday.

Mr. Hagel and General Dempsey indicated they are open to considering the request of President Recep Tayyip Erdogan of Turkey for a buffer zone along the Turkish-Syrian border, where tens of thousands of Syrians have sought refuge. Mr. Hagel said, “We’ve discussed all these possibilities and will continue to talk about what the Turks believe they will require.” He said 1.3 million Syrian refugees are now in Turkey.

General Dempsey added that “a buffer zone might at some point become a possibility,” but he said it was not imminent. Creating a buffer, or no-fly zone, would require warplanes to disable the Syrian government’s air defense system through airstrikes.

Both men spoke as the Pentagon continued its own airstrikes against the Islamic State. The extremist group is battling President Bashar al-Assad of Syria and Syrian insurgents backed by the United States — a complication of the American military campaign in Syria that began this week.