Defining the nature of Turkish-US relations has become a challenge in itself. Although institutionalised and historical, these relations are suffering from an accumulated series of crises, an outdated framework, and diverging threat perceptions. A glimpse into the files on both countries’ agendas in recent years clearly confirms the nature of their relations.

Yet nowhere have the problematic aspects of these bilateral relations manifested themselves as clearly as in the context of Syria. Strategic incoherence and geopolitical incompatibility have been the defining qualities of Turkish-American policies in Syria. Both actors' visions, goals and threat perceptions were diverging. They mistrusted each other’s local alliance structures, seeing them through the lenses of terrorism. By emphasizing the Kurdish People’s Protection Units’ organic links with the Kurdistan Workers’ Party (PKK), Turkey accused the US of allying itself with the offshoot of a designated terrorist organization. In contrast, Brett McGurk, the former US envoy for the anti-ISIS coalition, in an op-ed for The Washington Post depicted Turkey’s allied Syrian opposition groups as being "marbled with extremists." Rather than being personal, this line of thinking appears to have a constituency within the US security and foreign policy establishment.

Although the Syrian imbroglio has aggravated Turkey-US relations and added new items to the list of growing numbers of unresolved crises between both actors, it is not the sole source for the downward trajectory in their relations. The Syrian crisis is the cause, but also a symptom of a deeper crisis in these relations. Strategic decoupling and geopolitical incompatibility between both countries have been real and ongoing for some time. The Cold War framework of their relations is not working anymore. Yet both countries have yet to come up with a new framework to replace the old and by now dysfunctional one. At a time when the elite and institutional ownership of these relations are fraying, the institutional mistrust between Turkey and the US is growing, particularly at the military level.

In fact, this was glaringly visible during discussions about a safe zone in Syria. Whereas the personal ties between presidents Recep Erdogan and Donald Trump are relatively positive and improving, the institutional gap between both countries has remained wide. The positive news for Turkey is that with each new governmental appointment, the previous gap between Trump and the US administration is fast disappearing. The downside is that Trump appears to operate according to his impulses and instincts, rather than through well-thought-out policy visions. This in return reveals the need to reinvigorate the institutional ties and partnership between Turkey and the United States within a rectified framework, which takes into account the realities of today's world, not the assumptions of the bygone era of the Cold War.

Nevertheless, as a result of the strategic decoupling between Turkey and the US, which has been further aggravated by the weakening of the traditional elite and institutional ownership of these relations, Turkey has pursued “flexible alliances” in recent years. Relations with Russia and Iran are cases in point. From cooperation within the framework of the Astana and Sochi processes on Syria to Turkey's purchase of Russian S-400 missiles, in any Russian-Turkish engagement, there has always been an invisible third party, the United States, which defined the nature and quality of these engagements.

Likewise, Turkey-US interactions, particularly on Syria would involve Russia as an “invisible third party” that influences, constrains and even shapes the course of these interactions. This is why after interaction with Trump and the US officials in December and January, President Erdogan was keen to meet with Russian President Vladimir Putin to discuss the new phase in Syria.

In a similar vein, discussion of Turkey’s purchase of the S-400 air defense system from Russia is no longer confined to the defense industry. Rather, the purchase is seen as reflecting Turkey’s new geopolitical choices. Despite Turkey’s desire to keep discussion solely on its defense and security needs, the United States views the purchase through Turkey’s new geopolitical alignment, irrespective of whether this alignment is real or not. To counter this, Turkey is striving to make sure that the purchase is not regarded as indicating Turkey’s preference for deepening ties with Russia at the expense of its historical and institutional ties to NATO and to the West in general. But this is exactly how the United States and NATO interpret the Turkish decision.

Recent remarks by General Curtis Scaparrotti Supreme Allied Commander Europe of NATO Allied Command operations, in which he said that Turkey could not have both the S-400 and the US-built F-35 stealth fighter, shed light on the mood in NATO circles. It wasn’t only the message, but the identity of the messenger, that gave the statement added importance.

Despite repeated pleas and warnings from the West, Turkey is unlikely to backtrack on its purchase. Doing so would negatively affect Turkish-Russian relations, particularly in Syria – a situation that Turkey will strive to avoid.

Irrespective of the framing, we are heading toward another major crisis in US-Turkish relations, which is likely to manifest itself on multiple fronts. The immediate repercussions will be felt in security and defense cooperation between Turkey and NATO. Second, the crisis will have geopolitical consequences. The distance between Turkey and the United States will widen in some major crisis areas, such as northeastern Syria. Cooperation and coordination will likely prove even trickier. Third, Washington is likely to impose sanctions on Turkey’s financial and defense industries, including blocking delivery of the F-35 to Turkey. This, in turn, will invite further discussions inside and outside Turkey about the country’s geopolitical identity and orientation. And all this will take place at a time when previous assumptions about NATO and the trans-Atlantic alliance are being challenged by both members of the alliance themselves and by NATO’s foes.

As seen in recent years, Turkey is increasingly stuck between its fraying traditional alliance structure and fragile new partnerships. Unless Turkey and the US revisit the present dysfunctional framework of the relations, the divergence will become not an aberration in their relations, but the new normal for them.

This article is based on the author’s recent pieces on the same subject for Le Monde, The German Marshall Fund of the United States, and the Carnegie Endowment.