There are two story lines about the Russian-Turkish relationship that have been circulating in the past few years. One is that the leaders of these two states, Vladimir Putin and Recep Tayyip Erdogan, have become increasingly close as a result of their resentment of American and European policies as well as their determination to thwart them. The other is that Moscow and Ankara are increasingly at odds over important issues such as Syria and Libya. The question, then, is will the impressive cooperation that Putin and Erdogan have achieved allow them to overcome their serious differences, or will their differences be so severe that they negatively impact both their willingness and ability to cooperate? Or will they somehow be able to maintain their current level of cooperation despite serious differences between them?

And those differences are serious, especially in Syria where the Russian-backed Assad regime’s determination to retake Idlib from the Turkish-backed Syrian opposition there is now coming to the fore. What Ankara fears is that if the Assad regime retakes Idlib, a flood of refugees will stream north into Turkey where Ankara is already struggling to support previous waves of refugees from the Syrian civil war that has been going on since 2011. Further, if the Assad regime retakes Idlib, it may then seek to retake areas further north that Turkey now has influence over, such as Afrin. Conflict between Turkish and Assad regime forces involving Russian personnel has already occurred and could grow worse. A similar dynamic may be developing in the conflict between Libya’s U.N.-recognized government and General Khalifa Haftar in which Turkey is aiding the former and Russia (via private military contractors) is helping the latter.

The fact, though, that Putin and Erdogan have established an impressive degree of cooperation over the past few years, raises the possibility that they will be able to contain, if not completely overcome, their serious differences in Syria and Libya. The rebound in their relations less than a year after the low point they reached in November 2015 when Turkish forces shot down a Russian military aircraft suggests that Putin and Erdogan may be able to overcome other differences as well. Erdogan’s belief that America and Europe supported the attempted coup against him in July 2016 while Putin supported him aided this earlier rapprochement greatly.

But can their sharing of grievances against the West allow Putin and Erdogan to overcome their current differences as occurred in 2016? The problem is that while each objects to American and Western policies, they do not object to the same ones. Putin is angry with the West over its economic sanctions against Russia over its annexation of Crimea and other actions in Ukraine. But while Erdogan has not joined this Western campaign against Russia, he does not support what Putin has done in Ukraine either. Similarly, while Erdogan is incensed with the U.S. for supporting Syrian Kurdish forces whom he sees as allied to the Kurdish opposition inside Turkey, Moscow reached out to the Syrian Kurds and offered to mediate between them and the Assad regime after U.S. President Donald Trump announced that he was going to withdraw American forces from northeastern Syria.

In the Middle East’s various conflicts, Moscow’s preferred approach is often not to completely side with one party against the other, but to try to maintain good relations with both. In Syria, for example, Moscow is largely content with helping the Assad regime control what for Russia is “useful Syria.” It is not crucial for Moscow that Assad regain lost territory in Idlib or elsewhere. Indeed, Moscow could live with Turkey having predominant influence in those areas near the Syrian-Turkish border either because of its fears about increased Syrian refugees or Kurdish influence. The problem, though, is that the Assad regime is not willing to live with Turkish influence is northern Syrian, and so is actively seeking to expel it.

Turkey would like Russia to restrain its Syrian allies, but Moscow has proved either unwilling or unable to do so. Indeed, Moscow may feel compelled to support the Assad regime’s actions for fear either of losing influence to Iran, or worse, risking Syrian government forces being defeated by Turkish and Turkish-backed Syrian forces. At best, this could end Moscow’s hopes to pacify Syria sufficiently to attract outside economic investment from the Arab Gulf and even the West that Moscow hopes (however unrealistically) to encourage. At worst, an Assad regime setback could lead to revived opposition against it more generally which Moscow does not wish to see.

In Syria in particular, then, the differences between Moscow and Ankara are over high stakes issues for both sides. And it is not at all clear that common antipathy toward American and European policies will be able to help Putin and Erdogan overcome them this time.