America’s relationship with Turkey deteriorated sharply early this month, when Washington gave Ankara a deadline of 31 July to cancel its purchase of the Russian S-400 air defence system or face having its participation in the F-35 fighter jet project discontinued. The US also threatened Turkey with sanctions under the Countering American Adversaries Through Sanctions Act ^[1] if it decided to go through with the S-400 purchase.

Washington has stated ^[2] that it opposes the purchase because it ‘does not want to have the F-35 in close proximity to the S-400 over a period of time because of the ability to understand the profile of the F-35 on that particular piece of equipment’. It has also noted ^[3] that the S-400 procurement would hinder Turkey’s ability to enhance or maintain cooperation with the US and within NATO and would lead to ‘Turkey’s strategic and economic over-dependence on Russia’.

Ankara has since doubled down on its commitment to buy the S-400. Turkish President Recep Tayyip Erdoğan maintains ^[4] that it is a ‘done deal’ and that he hopes that the system will be delivered to Turkey in July. Erdoğan also indicated that he would seek answers on Turkey’s exclusion from the F-35 project for ‘reasons that have no rational or legitimate basis’.

The financial ramifications of Turkey’s US$2.5 billion purchase of the S-400 system are significant, and the procurement will jeopardise Turkey’s membership of NATO ^[5] and its relationship with the US. Turkey is seeking to purchase up to 100 F-35s and has already invested around US$1.25 billion in the project. Turkey’s defence industry produces more than 900 components for the F-35, and its participation in the co-production element of the F-35 program is estimated ^[6] to be worth US$12 billion. Ankara’s apparent willingness to risk all of this by purchasing the S-400 is therefore curious, particularly given that Washington has offered ^[7] Turkey the Patriot PAC-3 MSE missile system for US$3.5 billion, less than half the cost of an earlier offer, if Ankara cancels its S-400 order.

Ankara may be thinking that Washington won’t go through with its threat to suspend Turkey’s participation in the F-35 program and that US President Donald Trump will overrule the Pentagon’s position. Turkey’s foreign minister, Mevlüt Çavuşoğlu, alluded to this view during a press conference on 13 June. Çavuşoğlu referenced ^[8] a Turkish proposal for a two-way technical committee to study the impact of the deployment of the S-400 on Turkish soil on the integrity of the F-35 platform and noted that ‘President Trump says “Yes” but other institutions say “No”’.

It’s also possible that Ankara is committed to the S-400 purchase because it addresses its strategic objectives better than the Patriot alternative. The S-400 has a significantly greater range ^[9] than the Patriot and provides Turkey with an anti-access/area-denial capability that would give it a significant strategic advantage ^[7] over regional rivals such as Greece or Syria.

Nevertheless, Erdoğan’s administration is increasingly antagonistic ^[10] towards Washington, and Ankara’s broader behaviour is aggravating other NATO partners. Issues ^[6] such as Washington’s arming of Kurdish People’s Protection Units (YPG) in northern Syria and its refusal to extradite Turkish cleric Fethullah Gülen ^[11] have also not helped relations. Given this context, it is possible that the S-400 procurement is a deliberate move by Ankara towards closer alignment with Moscow, at the cost of its partnership with NATO and the US.

In some respects, Erdoğan and Russian President Vladimir Putin are natural bedfellows. They share similar authoritarian tendencies and have pursued domestic programs that have marginalised the media and undermined the rule of law. Erdoğan and Putin also arguably ^[12] share a scepticism of Western policies and political systems.

Turkey and Russia are also increasingly interlinked economically ^[13]. Turkey is heavily reliant on Russian gas for its energy security—it uses natural gas to produce 60% of its electricity and gets over half of that gas from Russia. And it will become more dependent ^[14] on Russian gas as a consequence of Russia’s partnership in the TurkStream gas pipeline project.

But Turkey and Russia have also long been strategic competitors and historically their relationship has been characterised by conflict rather than cooperation. Turkey and Russia have disagreed on Syria more than they have agreed, and Turkey’s downing of a Russian warplane on the Turkish–Syrian border in 2015 saw tensions between the two countries escalate and Moscow retaliate by imposing sanctions on Ankara.

The two countries have since reset relations but sources of tension ^[15] remain. Ankara is still not reconciled with Moscow’s support for the Assad regime in Syria. Turkey has also refused to recognise Russia’s annexation of Crimea and is concerned that Russia’s militarisation of the Black Sea and its expanded military footprint in Syria, Armenia and Georgia’s secessionist regions of Abkhazia and South Ossetia will lead to encirclement. Russia and Turkey also support opposing sides in the frozen conflict between Azerbaijan and Armenia in Nagorno-Karabakh. The relationship is defined by an asymmetry ^[12] that clearly gives Russia an advantage over Turkey, which Moscow will likely exploit ^[14]. Moscow probably sees the S-400 sale as a tool for driving a wedge between Turkey and its NATO allies.

Ankara’s current disposition towards Moscow reflects a marriage of convenience rather than the consolidation of a durable partnership. The US, in developing its response to Turkey’s S-400 purchase, needs to recognise that this issue is a symptom and not the cause of the fundamental problems at the heart of Turkey’s alliance with the US and NATO. Washington must decide whether Ankara is a reliable partner and balance that assessment against the cost of losing Turkey as a key ally in the Middle East. More effective use of diplomacy and defence assistance ^[6] may help the US preserve its alliance with Turkey, but the window of opportunity to do so will soon close.