Set on the Euphrates River inside Syria, a centuries-old tomb complex considered Turkish territory has become a new potential flashpoint in the conflict with jihadists that could be crucial in determining Ankara's future policy.
For decades, few paid much attention to the quirk of history that had left the tiny scrap of land inside Syria that houses the tomb of Suleyman Shah -- the grandfather of the founder of the Ottoman Empire Osman I -- as sovereign Turkish territory.
But with Islamic State (IS) jihadists controlling swathes of northern Syria and now bearing down on the tomb itself, the exclave has become a critical factor in Turkey's sometimes ambiguous, but now changing, role in the conflict.
The tomb of Suleyman Shah, around 25 kilometres south of the Turkish border, is considered Turkish territory under the 1921 Treaty of Ankara between the Turkish authorities and France, which then controlled French-mandated Syria.
Turkey has maintained a continuous military presence to guard the tomb but the position of the few dozen troops stationed there has become all the more precarious amid the IS militants' advance.
President Recep Tayyip Erdogan has indicated that Turkey would strike back if there was an attack on the tomb, saying its answer to any aggression would be "clear".
Furthermore, if the tomb was attacked NATO member Turkey could in theory invoke Article V of the alliance's treaty that an attack on one member is an attack on them all.
In a sign of the seriousness of the situation, Turkey's top general Necdet Ozel today issued a special message for the soldiers on duty at the tomb, saying the army would come to help them whenever they needed.
"Don't forget that you are not alone. Don't forget that 76 million of our citizens are committed to standing behind you," he told the troops guarding Turkey's only overseas territory.
"Feel confident that our armed forces will be there for you the moment we hear a single word from you," he added.
The tomb was for years guarded largely by conscripts but in March this year Turkey reportedly sent a special mission of 60 elite special forces who remain on duty there to this day.
The Turkish leadership has vehemently rejected a report in the pro-government Yeni Safak daily that the tomb had been surrounded by some 1,100 IS militants and the Turkish soldiers taken hostage.
But Defence Minister Ismet Yilmaz acknowledged in parliament today that IS was advancing on Suleyman Shah, describing its progress as "a threat to our national security."
Some press reports have suggested the general staff was unhappy that Prime Minister Ahmet Davutoglu did not allow the evacuation of the troops. However not a flicker of dissent has emerged from the military in public.
Turkish media have said the armed forces have developed a plan to repel any IS attack within 15 minutes through attack helicopters.
