The Turkish military launched an operation into Syria overnight to evacuate Turkish soldiers guarding the tomb of Suleyman Shah, grandfather of the founder of the Ottoman Empire.

The mission was successfully completed, with the troops brought back to Turkey, but one soldier was killed in an accident during the operation, one of the officials said.

The Turkish government said late last year that Islamic State militants were advancing on the mausoleum, which is guarded by several dozen Turkish soldiers.

The tomb was made Turkish territory under a treaty signed with France in 1921, when France ruled Syria. Turkey regards it as sovereign territory and had repeatedly vowed to defend it from any attack by the insurgents.

Turkey has been reluctant to take an active role in the U.S.-led military campaign against Islamic State, partly because it wants to see the military action target Syrian President Bashar al-Assad's forces as much as the insurgents.

Islamic State and other Islamist groups, whose strict Salafi interpretation of Islam deems the veneration of tombs to be idolatrous, have destroyed several tombs and mosques in Syria.

The remains of Suleyman Shah will be moved to a different area of Syria which has been brought under Turkish military control.