ISTANBUL, Turkey — Relations between once close allies Iran and Turkey are rapidly deteriorating over Ankara's strong support for Syrian rebels fighting against Iran's key ally, Syrian President Bashar al-Assad. In an unprecedented move, Tehran suspended visa-free travel with Turkey for the first time in nearly 50 years.
Iran observer Mehrdad Emadi, who works for the international affairs consultant firm "Betamax," said the suspension of visa-free travel is significant.
"It is quite actually meaningful in the context of the rising tensions between the two countries," said Emadi. "And, I think there are too many sources behind this growing tension - one is the conflicting positions in the management of the Syrian crisis. We have never had such a thorny relationship between the two countries."
Iran alienates Ankara
Iranian leaders and senior diplomats increasingly have toughened their rhetoric against Ankara. Turkish Prime Minister Recep Tayyip Erdogan this week accused Tehran of being ungrateful for his government's efforts to defuse international tensions over Iran's controversial nuclear program. Two years ago, Turkey - as a temporary member of the U.N. Security Council - voted against Iran sanctions.
Former senior Turkish diplomat Murat Bilhan said it is difficult to read Iran.
"The Iranian chief of general staff threatens Turkey in a press conference, but then the minister of foreign affairs denies it. Which one are you to believe?" asks Bilhan.
Bilhan said one factor behind the mixed messages is that Tehran is looking to Ankara to use its contacts to secure the release of 48 Iranians seized by rebels in Syria.
But Iran watcher Emadi said it also could be a sign of divisions within Iranian leadership.
"It has never been more disunited and uncoordinated in regards to its foreign policy."
Kurdish remains key concern
One other worry for Ankara is the major long-standing Kurdish issue.
Tehran during the 1990's provided support to the Kurdish rebel group the PKK in its fight for greater minority rights in Turkey. Emadi said Tehran might again be tempted to use the PKK against Ankara, but said it's a dangerous game.
"Iran has a very large Kurdish population and in recent years this population has become more vocal and most restive. But Iran sometimes has opted very, very high-risk options."
Some experts forsee rough road
Political columnist for the pro Islamic newspaper Yeni Safak, Akif Emre, said with Iranian-Turkish relations now linked to the crisis in Syria, tensions could worsen.
"If the crisis is getting deeper, that means the Iran and Turkish problem is getting deeper. This is very dangerous. The Syrian crisis is not limited to Syrian national borders. It could become a real regional crisis, maybe war," said Emre.
This Saturday, Turkish Foreign Minister Ahmet Davutoglu will host U.S. Secretary of State Hillary Clinton to discuss support for the Syrian opposition.