President Recep Tayyip Erdogan of Turkey has long cast himself as a champion of the Arab Spring uprisings and the political Islamists who once seemed poised to ride them to power.
Crown Prince Mohammed bin Salman of Saudi Arabia anchors the opposite camp in an ideological battle raging across the Middle East: the anti-Islamist strongmen who quashed the revolts.
The two leaders, each the head of a major regional power, have until now kept their relations cordial in the interest of stability. But over the past week, tensions between them have erupted over the disappearance of Jamal Khashoggi, a Saudi dissident and Washington Post columnist who vanished after entering the Saudi Consulate in Istanbul nine days ago.
Mr. Erdogan has repeatedly challenged Saudi Arabia to explain Mr. Khashoggi’s disappearance, while Turkish officials say they have video and audio evidence proving he was killed, and have unleashed a stream of leaks suggesting that the royal court ordered it. The crown prince and his spokesmen have insisted, without providing evidence, that Mr. Khashoggi left the consulate freely, professing that they, too, are worried about him.
The dispute pits two staunch, headstrong nationalists against each other — both with ambitions to reshape their region. They also share an aversion to public criticism and a history of refusing to back down from a fight.
“These are two people who each think he is the most important person in the Muslim world,” said Steven A. Cook, a scholar at the Council on Foreign Relations who studies both countries. “Ego is a factor on both sides.
On Thursday, there were signs that the two leaders were looking for a way out. Mr. Erdogan’s office announced that he had agreed to a Saudi request to form a joint “working group” that will examine Mr. Khashoggi’s disappearance.
Certainly, each man has much to lose.
Mr. Erdogan is struggling to manage a teetering economy and his entanglement in war-torn Syria. He can ill afford a new battle with a deep-pocketed regional power like Saudi Arabia.