After the U.S. and Turkey agreed to intensify their efforts to fight against the Islamic State of Iraq and al-Sham (ISIS) via opening İncirlik Air Base and three other air bases in Turkey for coalition airstrikes and setting up a safe zone or no fly zone inside Syria, another discussion has been sparked regarding the scope of the zone. While some analysts assert that there is no agreement between Turkey and the U.S. to create such a zone, others says there is already de-facto no-fly zone in Syria and therefore there is no need for an official declaration.

Pentagon officials said earlier this week that the U.S. will begin to work with Turkey to clear out the last stretch of the Turkish-Syrian border, nearly 98 kilometers, controlled by ISIS and create an ISIS-free zone. Accordingly, the territory for a no-fly zone stretches from Jarabulus, a town that sits just west of the Euphrates River, to Azaz, a Syrian border town across from Kilis in southeastern Turkey. Likewise, Foreign Minister Mevlüt Çavuşoğlu said last week that a safe zone on the Turkish-Syrian border will be set up "naturally" if ISIS militants are cleared out of the area. Supporting this argument, a U.S. State Department spokesman said on Monday that coalition aircraft can freely fly over that area without being challenged by the Syrian regime or ISIS. Brett McGurk, deputy special presidential envoy for the Global Coalition to Counter ISIS, also supported the same view by saying that there is already a de-facto no-fly zone in Syria and stressed no need to declare a no-fly zone inside Syria. "We have done 5,600 airstrikes up until now and 40 percent of them are in Syria. When we strike, we strike with great density and the Syrian regime does not come anywhere near. We do not see the need for a declared no-fly zone. For example, when we are operating from Kobani, it is a de-facto no-fly zone. We have been clear to the regime that we are there to strike ISIS and so far, they've clearly gotten the message," McGurk said on Tuesday evening on the Charlie Rose show.

Legal authority for creating no-fly zones comes from Chapter 7, Article 42 of the U.N. Charter, and the U.N. may authorize "demonstrations, blockade, and other operations by air, sea or land forces" Thus, the first step is obtaining a mandate from the 15-member U.N. Security Council (UNSC). Thereafter the five permanent members on the UNSC – the U.S., U.K., Russia, France and China –also need to approve the decision. The 2011 Libyan no-fly zone case is the most recent example of a U.N.-created no-fly zone. In 2011, China and Russia opposed the plan of a no-fly zone over Libyan air space but they were persuaded by advocates to abstain from the vote. However, Russia and China declared their position for the Syrian no-fly zone to block the action with a veto, so the UNSC issuing a resolution authorizing a no-fly zone in Syria seems a remote possibility.

The purpose of establishing the zone is reportedly be to ensure the protection of some Syrian rebels along with civilians escaping ISIS, which has taken over large parts in Syria and Iraq, and the Assad regime. The zone, if implemented, would also increase the safe flow of humanitarian supplies to Syria. Turkish officials said earlier this week that the safe zone is to provide conditions for refugees to return to Syria. Prime Ministry sources reported that the necessary steps, which require providing conditions for refugees to return to Syria, were discussed in the last Cabinet meeting and accordingly, after cleaning the proposed safe zone of ISIS militants and other threats, the Disaster and Emergency Management Agency (AFAD) will build refugee camps inside Syria as a first step. Other infrastructure investments such as building roads, permanent accommodations, schools and hospitals are planned as a next step in order to attract refugees to return to Syria, sources said.