Long resisted by the US for its impracticality and because it was considered too big a concession to Turkish interests, the concept of a 'no-fly zone' in northern Syria now appears to have morphed into a so-called 'safe zone'. The plan, as far as it appears to have been enunciated, involves US and Turkish aircraft (flying from Incirlik in Turkey) and possibly Turkish artillery assisting as yet unknown Syrian opposition forces to clear ISIS from as yet unknown swathes of northern Syria. Once areas are cleared of ISIS, the safe zone(s) will develop naturally, according to the Turkish foreign minister. An interesting concept.
There is often a substantial gap between announcements and execution, but this proposal has the potential to significantly change the dynamic in Syria, and possibly muddy the waters further. Here are some concerns, in the absence of much detail:
Who makes the 'safe zones' safe?
Air power alone can't do it, so there has to be a significant ground component, supported by air strikes, to seize and hold territory. While there has been some commentary that the hitherto ineffectual Free Syrian Army may be strengthened (yet again) in order to do the job, this is unlikely to occur quickly, opening up the distinct possibility that the safe zone could be held and cleared in part by anti-ISIS jihadist groups, of which there is no shortage in northern Syria.
One could even mount an argument that the recent media appearances by jihadist groups such as Ahrar al-Sham and Jabhat al-Nusra on al-Jazeera and in The Washington Post (which I have commented on previously) have been about positioning themselves as 'acceptable' jihadis. When the New York Times describes the plan as involving the use of 'relatively moderate' insurgent groups rather than simply 'moderate' groups, it's time to start worrying.
Things rarely occur 'naturally'
The 'naturally occurring' safe zones may allow some Syrian refugees to return to Syria, but how would these people survive? What humanitarian assistance would be provided to them and by whom? Who would provide the governance and security functions within these zones? What would be the Syrian Government's approach to them and what would the international community do if the Assad regime sought to reassert its authority over the parts of Syrian territory cleared of ISIS? Nature and politics abhor vacuums, and once safe zone(s) are created, there will always be someone who seeks to take advantage of them. The UN certainly has some concerns about the prospect of a safe zone, particularly given the lack of detail released to date.
Turkey isn't doing this for altruistic purposes
The Turkish Government has long stood accused of not doing enough to combat ISIS because President Erdogan saw Assad as the primary enemy, and because of the Government's Islamist proclivities. But now with the ISIS bombing of the town of Suruc and ISIS attacks against Islamist groups over whom Anakra has more influence, Turkey finally sees a need to join the West's campaign against the group. With the signing of the recent Iranian nuclear agreement as well, Ankara may well have concluded that it is time to accelerate its role in Syria before the easing of sanctions gives Tehran a freer hand to assist Damascus. So while Turkey may not actually occupy these safe zones, the fact that Ankara will control all the entry points means Turkey effectively controls them, and will be able to support those groups who wish to fight Assad rather than ISIS. For Ankara, this is potentially a big win.