Turkey's capture of the northwestern Syrian city of al-Bab from Islamic State (ISIS) militants has put Ankara at a crossroads where its choices are to either: 1.) consolidate its gains and secure these captured territories; or 2.) push on to attack the Kurdish-led Syrian Democratic Forces (SDF) in nearby Manbij, and possibly ISIS in Raqqa, too. 

“Turkey and the FSA [Free Syrian Army] have cleared some of the main strongholds of Daesh [ISIS], including Dabiq, Jarablus and al-Bab, and are likely to continue with clearing Manbij and Afrin of Democratic Union Party (PYD) terrorists,” read a recent article in Turkey's pro-government Daily Sabah. 

If this turns out to be correct it would be a dangerous move for Turkey to make. An attack on Manbij will likely see more SDF fighters rush in from the east to defend that city and the SDF's Manbij Military Council there. An attack on Afrin would certainly result in war between Ankara and the SDF/YPG, since Afrin is part of Syria Kurdistan proper. This, for obvious reasons, would result in SDF manpower and resources being diverted away from the Raqqa offensive.

Ankara has repeatedly said for a long time that if the PYD's armed wing, the People's Protection Units (YPG), were to capture Raqqa it would have severe repercussions. Aside from arguing that backing a YPG operation in Raqqa is a flawed policy of replacing one terrorist group with another in Raqqa, Ankara has also been insisting that using this group to take Raqqa could lead to destabilizing ethnic tensions. 

“More than 90 percent of the Raqqa population is Arab,” said Turkish Defense Minister Fikri Işık on February 23. “If you assign a terror organization with a different ethnic background to save the city, you would cause big instability. The same was also valid for Mosul.” 

Turkey initially acquiesced to the SDF's offensive into the Arab city of Manbij because mostly Arab fighters were assigned to spearhead that operation – with a small supporting force of Kurdish YPG fighters. Just two days after Işık's comment the official US Central Command's (CENTCOM) Twitter page published photos of Syrian Arab members of the SDF they are training. The Manbij model, using Arab-majority SDF units to liberate Arab cities, is clearly being followed in the Raqqa operation, a fact which should assuage Işık's concerns of possible ethnic tensions. Arab tribesmen fighting under the flag of that coalition will likely be welcomed by Raqqa's population as liberators as much as, if not more than, any Arab FSA, or other, force Ankara could muster for the same unenviable undertaking. 

Turkish President Recep Tayyip Erdogan has repeatedly, for months now, vowed to advance against Manbij, and even Raqqa, once al-Bab was captured. In Manbij he wants to rout the SDF/YPG, who captured the city back in August. In Raqqa, he's said Turkey could even defeat ISIS and establish a safe zone for displaced Syrians there. However, on all these points, Turkish officials have given notably different assessments. The most striking one, which runs directly contrary to Erdogan's assertions, was from Deputy Prime Minister Numan Kurtulmus, who said in a recent statement, before al-Bab's capture, that: “With al-Bab, Euphrates Shield will be over as goals will have been achieved. Raqqa is something else. It doesn't threaten Turkey's borders.” 

Also, Turkish Prime Minister Binali Yildirim said that Turkey will not get directly involved in the Raqqa operation, but instead play a tactical supporting role.

“The United States, Turkey along with local forces, civilian forces, and FSA and other militias... They are at the forefront while we are at the back,” Yildirim said, according to Anadolu.  

Kurtulmus also previously said, late in January, that his government has no intention of handing al-Bab over to the Syrian regime, whose forces control the road from Deir Hafir to the city's southeast.

Sitting tight in al-Bab and the northwestern territories it captured since August would solidify Turkey's primary objectives in northwest Syria: pushing ISIS south of its border, preventing rocket and terrorist attacks against Kilis, and other areas in Gaziantep, and the SDF/YPG from linking Afrin to the rest of their territories east of the Euphrates River. SDF/YPG-controlled territories — the so-called Shahba region protruding out of Afrin to al-Bab's west and Manbij to its east — cannot be connected by these groups to form a continuous Syria Kurdistan while the Turkish military and/or FSA maintain a formidable presence in al-Bab. 

So, provided the SDF/YPG do not attack Turkish-FSA forces in these areas, and vice versa, both sides should remain in a de-facto ceasefire mode, in subtle recognition that an escalation of clashes will destabilize that corner of Syria and affect both of them negatively. 

Were Turkey not to take this course and assault Manbij — or worse Afrin — it could fatally undermine, or completely compromise, the efforts the US has been undertaking to make the SDF a competent force capable of seizing Raqqa and giving ISIS in Syria a mortal blow.