The two countries appear to be compartmentalizing their shared and divergent interests in Syria and Iraq, but such an approach is highly vulnerable to unexpected military incidents and other factors.
Turkish and Iranian officials have conducted a number of high-level bilateral visits recently, suggesting that the two countries are drawing closer after a period of serious disagreements over Iraq and Syria. What is driving this rewarming, and how sustainable is it?
FROM THE AKP TO THE ARAB SPRING
Turkish-Iranian ties blossomed in the last decade under the Justice and Development Party (AKP) government. Whereas previous, secular-based Turkish governments took a dim view of Iran, the Islamist-rooted AKP sought to build the relationship after coming to power in 2002. High-level visits and trade deals ensued, and by 2010, the United States was urging Ankara to help mediate an abortive nuclear deal with Iran called the "Tehran Agreement." When Washington later found that deal unsatisfactory, Turkey voted against the subsequent U.S.-sponsored resolution at the UN Security Council that increased sanctions on Iran.
Yet relations between Ankara and Tehran began to deteriorate when the Arab Spring uprisings broke out in 2011. They were particularly at odds over Syria's civil war -- Turkey threw its lot behind the rebels, whereas Iran stood fast with Bashar al-Assad's regime, its long-time client. As a result, they became locked in a proxy war, with Ankara arming and sheltering the rebels, Tehran funding Assad's military and sending forces to fight on his behalf, and both countries issuing fierce public criticisms of each other's stance in Syria.
Differences have also arisen over Iraq, where Turkey's warm ties with the Kurdistan Regional Government (KRG) have angered the Shiite-led government in Baghdad and its ally in Tehran. Moreover, Iraq has taken issue with Turkey's encroachment into the country's Sunni Arab northern region. Most recently, Baghdad -- with Iran's backing -- asked Turkey to evacuate the Bashiqa base near Mosul where Ankara has built a military presence in recent years.
EASING THE TENSION
In the past few weeks, Ankara and Tehran have signaled that are trying to set aside their differences. Turkish foreign minister Mevlut Cavusoglu traveled to Tehran on August 18 after his Iranian counterpart Mohammad Javad Zarif visited Ankara on August 12. The main reason for this rewarming seems to be Syria.
The August 24 Turkish incursion into Syria -- which occurred with Russia's tacit blessing and direct, if limited, U.S. military support -- is a telling development in the relationship. It shows that the war is evolving into many mini-conflicts in which opponents on one front (Turkey vs. Russia in Aleppo) can cooperate on another front (Jarabulus). It also shows that actors are preparing for the "day after" the Islamic State (IS) and shifting their priorities accordingly. For instance, Turkey no longer seems completely preoccupied with ousting Assad. Instead, by brokering a tacit peace with Russia and, implicitly, Iran, Ankara is preemptively acting to take areas that would otherwise be captured by the Democratic Union Party (PYD), the Kurdish group that has seized much of the northern border region and would be one of Turkey's chief adversaries in a post-IS Syria.
To be sure, President Recep Tayyip Erdogan and his top Foreign Ministry officials have continued to speak out against Assad since last month's incursion, raising questions about whether Turkey can truly abandon its policy of ousting him. Yet Ankara is cognizant of the fact that the current regime -- and maybe even Assad himself -- will likely survive for some time, so lately it has asked its proxies in Syria to focus more on efforts to block PYD advances.
In short, the thaw with Iran does not appear to be a strategic shift, nor should it be interpreted as a sign that Turkey intends to leave NATO down the road. Ankara will continue to disagree with Iran's main goals in Syria.
For its part, Tehran sees the thaw as an opportunity to curry favor with Ankara and dampen Turkish objections to the Assad regime's survival. Iranian leaders may even have asked Assad to order the recent Syrian military bombing of PYD positions in Hasaka province as a way of winning over Ankara.
THE ECONOMIC FRONT
Prior to the recent military and diplomatic cooperation, the pressure of facing two powerful adversaries in Syria spurred Turkey to extend an economic olive branch to Tehran. This helped Iran find relief from international sanctions, and Tehran reciprocated by inviting Turkish businesses into the Islamic Republic.
Efforts to integrate their markets have been particularly robust this year. On February 29, Tehran held the first Iran-Turkey Capital Markets Forum to facilitate the dual listing of companies on each country's stock exchange. On March 5, then-prime minister Ahmet Davutoglu called for removing bureaucratic trade impediments to take advantage of their complementary economies and geographies, arguing that this could help triple annual trade from $9 billion to $30 billion. And on April 9, the Iranian and Turkish Chambers of Commerce signed three documents to strengthen economic cooperation and banking relations following the twenty-fifth session of the Joint Economic Commission in Ankara.
Improved economic relations with Iran could also open possibilities with Baghdad. Turkey is deeply anchored in the increasingly independent KRG, but a closer relationship with the central government and its more than three million barrels per day in oil exports could bring additional diplomatic, energy, and trade benefits.
FUTURE COMPARTMENTALIZATION AND RISKS?
Given this assortment of shared and divergent interests, Turkey and Iran will likely decide to compartmentalize their relations on different fronts. For instance, while they will continue to disagree on some aspects of Syria policy (e.g., Assad's future and the battle for Aleppo), they would both object to any scenario involving Syrian Kurdish autonomy or independence. On the economic front, their relations will continue to boom. And in Iraq, they will likely settle on a political condominium over the Kurds, with Ankara wielding influence over one of the KRG's two main rival factions (the Kurdistan Democratic Party) and Tehran maintaining hegemony over the other (the Patriotic Union of Kurdistan).
Yet the course of Turkish-Russian relations has shown that any such compartmentalization approach is wrought with potential pitfalls. Up until late last year, Ankara and Moscow were able to develop deep trade and energy links even while disagreeing on Syria. In November, however, Turkey shot down a Russian jet that briefly entered its airspace, prompting the Kremlin to sever nearly all of those links and even impose bilateral sanctions in January. Similar problems could arise with Iran should the two countries' military personnel or proxies accidentally clash in Syria.
Other challenges lie in the ongoing negotiations for a peace settlement in Syria. If a deal is reached that preserves the Assad regime, Turkey's long-term instinct would be to not fully abide by its terms. Instead, Ankara would likely offer public support for the deal while continuing to arm anti-Assad rebels, thereby angering Tehran and Moscow. Erdogan would find it difficult to completely end Turkey's support to non-IS fighters in Syria while at the same time helping the United States fight IS -- after all, he and other AKP elites identify as political Islamists and believe that supporting Islamist rebels is the right course.
Accordingly, unless Washington convinces the Syrian opposition's Saudi and Qatari backers to cut financial support and fully acquiesce to a peace deal, Turkey would likely continue funneling some weapons and money to rebel groups, including extremist factions. Saudi Arabia would take a dim view of a U.S.-Russian deal in Syria, seeing it as handing the country over to Iranian/Shiite control. Yet even if Riyadh were to come on board with such a deal, some portions of the amorphous Saudi elite would likely reject it and continue helping the rebels, mainly via Turkey. In the long term, this seems like the biggest threat to Turkish-Iranian ties under a compartmentalization scenario.
Turkey is wary of the Iranians and their regional aims, but it also wants to pursue a pragmatic relationship because of the need for economic cooperation, particularly on energy. Speaking at the UN General Assembly earlier this month, Erdogan called for a safe haven in northern Syria spanning some 5,000 square kilometers -- much larger than the nearly 1,000 square kilometers of border territory currently controlled by Turkey and its rebel proxies. This suggests that Ankara will be the non-IS opposition's main sponsor in the north going forward. Iran and Russia may be willing to live with such a zone, but that would be a considerable climb-down from Assad's pledge to retake the entire country.
In the short term, the sustainability of Turkey and Iran's rewarmed ties will depend on the extent to which they can avoid a scenario similar to the November shootdown incident with Russia. It will also depend on whether Ankara can withstand Saudi pressure to boost support for anti-Assad jihadists.
Soner Cagaptay is the Beyer Family Fellow and director of the Turkish Research Program at The Washington Institute.