The apparent agreement between the United States and Turkey over the use of the Incirlik Air Base in southern Turkey includes the establishment of a partial no-fly zone over the Turkey-Syria border, unnamed sources said July 24, Hurriyet reported. The 90-kilometer (55-mile) line would be 40 to 50 kilometers deep, the sources said, and serve an attempt to prevent radical Islamist groups such as the Islamist State and Jabhat al-Nusra from gaining ground in the area. Fighter jets from the U.S.-led coalition would be allowed to use the Incirlik base for operations, in coordination with the Turkish military, to provide security over the area when necessary, including carrying out attack or exploration flights, the sources said. Artillery backing from the Turkish military is also under consideration. Syrian military jets would not be allowed to access the airspace. Earlier, Turkish media reported that the U.S.-led coalition may also receive access to at least two other bases as well. Turkish Prime Minister Ahmet Davutoglu said in a news conference that the Turkish air strikes against Islamic State targets inside Syria on July 24 were unrelated to the negotiations with the United States. Turkey is preparing itself for a military challenge in northern Syria and seems to have some kind of an understanding with the United States on what the next steps will be.