Turkey has long considered the tomb of Suleyman Shah to be its sovereign territory, even though it is located within the borders of Syria, a little under 30 kilometers (around 20 miles) south of the Turkish border in the Euphrates River Valley. An honor guard of around 40 Turkish troops monitored and protected the site, but as battle lines moved closer to the site, protecting the tomb became riskier. This security threat became even more acute when the Islamic State kicked off an offensive in the region that took territory from the Syrian Kurds and led to the siege of Kobani.
This offensive put Islamic State fighters in proximity to the tomb and threatened to draw Turkey into direct combat in Syria if the tomb and the soldiers stationed there came under attack. But Turkey and the Islamic State have maintained a quiet balance in the ongoing conflict. The militant group refrained from attacking the site, just as it has largely avoided any concerted effort to attack positions within Turkey. For its part, Turkey has stayed on its side of the border, most notably near Kobani, where it faced domestic and international pressure to become more involved. In essence, both sides have maintained an uneasy standoff.
Turkey did not lend direct military aid to Kobani, but it did allow various Kurdish forces from the region to pass through its territory. Coupled with the air power of the U.S.-led coalition (which Turkey has so far resisted supporting in any direct way such as by providing air basing with closer proximity), the Kurdish forces have not only broken the siege on the city itself, they have retaken much of the territory they originally lost in the area.
The recent Kurdish operational advances allowed for Turkey to open a relatively safe corridor to the tomb of Suleyman Shah while precluding serious combat through large swaths of Islamic State-held territory. This explains the timing of this weekend's mission to extract the Turkish guards, who had been stuck there beyond their planned rotation, and to relocate the remains of Suleyman Shah to a position near the Turkish border that is much easier to defend. The tomb, along with its honor guard, was a potential liability and essentially a hostage of its geography. Had the tomb been raided or the honor guard been captured or massacred, Turkish policymakers would have faced serious domestic blowback.
Turkey could have reinforced the site or pre-emptively attacked Islamic State positions long ago in an effort to further secure the tomb. Instead, it chose the least confrontational path, mitigating the ongoing risk that threatened to pull it into the Syrian conflict in a more overt way. While withdrawing from a weak position that the Islamic State could have overrun gives Turkey a freer hand to take military action to its south, the nature of this move indicates Turkey will continue its policy of staying out of the Syrian conflict.