Why Turkey Can’t Hand Over Its S-400 to the US: Russia’s Stance and the F-35 Debate

Russia recently reinforced its stance that Turkey cannot legally transfer its Russian-manufactured S-400 air defense systems to the United States. Russian Foreign Minister Sergey Lavrov addressed speculation at the United Nations General Assembly, emphasizing that the S-400 agreement between Moscow and Ankara, signed in 2017, included an end-user clause prohibiting the system’s sale or transfer to any third party without Russian consent. Lavrov’s statement underscored Moscow's strict adherence to the terms of this contract and its expectations that Turkey respects this limitation.

Background on Turkey’s S-400 Acquisition

The S-400 purchase by Turkey marked a significant pivot in its defense relationships, especially with NATO allies. The S-400 Triumf system, designed by Russia’s Almaz-Antey Corporation, is among the world’s most advanced air defense systems. It can engage up to 80 targets simultaneously and intercept ballistic and cruise missiles at ranges up to 400 km. The system’s acquisition by Turkey was controversial not only because of its capabilities but because it is incompatible with NATO defense protocols. In response, the US excluded Turkey from the F-35 stealth fighter jet program, one of NATO’s cornerstone defense initiatives. The US justified this by claiming the S-400 posed a risk of Russian intelligence being gathered on F-35 operations through close system proximity.

The US Proposal and Turkey’s Position

Reports emerged suggesting a potential resolution: senior US officials allegedly proposed that Turkey transfer its S-400 system to the United States or store it under American control at the Incirlik Air Base in southern Turkey. In exchange, the US would consider reinstating Turkey into the F-35 program. However, Turkey responded cautiously, neither dismissing the proposal outright nor showing enthusiasm. Sources cited by Greek media outlet Ekathimerini suggest Turkish officials rebuffed the idea of handing over the S-400 to the US. Instead, they reportedly offered to keep the system dormant, implying that Ankara isn’t yet willing to dismantle its strategic relationship with Moscow over the S-400.

While Turkey has not definitively ruled out a potential arrangement with the US, its defense ministry stressed that Ankara's stance on maintaining an independent defense policy remains firm. Turkish sources reiterated the importance of removing restrictions between allies, alluding to NATO’s foundational principles of cooperation and mutual security.

Russia’s End-User Certification Clause

Lavrov highlighted that Russia’s contracts explicitly outline end-user agreements to prevent unauthorized transfers. This clause is integral to Russian arms deals, ensuring that the system remains within the purchasing country’s control. Should Turkey proceed with any unauthorized transfer, it risks damaging its defense relationship with Russia and potentially facing penalties or reduced access to Russian technology.

The end-user clause is a standard feature in many high-value arms contracts worldwide, especially when involving sophisticated defense technologies like the S-400. Such contracts are crafted to ensure the original vendor’s interests are protected and to avoid the possibility of its sensitive technology falling into unintended hands. Lavrov’s comments serve as a reminder of the high-stakes nature of these agreements and the diplomatic tightrope Turkey must walk between two powerful allies.

What’s at Stake for Turkey?

For Turkey, the S-400 acquisition was not just about obtaining a capable defense system—it represented a strategic choice that diverged from its traditional NATO alignment. By purchasing from Russia, Turkey indicated its intent to pursue a more independent defense strategy. However, this decision has come with significant trade-offs, most notably the forfeiture of F-35 fighter jets, which would have given Turkey a technological edge in regional security.

Turkey’s insistence on retaining the S-400 is as much about sovereign choice as it is about defense needs. By retaining the system, Ankara signals to its NATO allies that it is willing to break from consensus if it serves its national interests, especially if it perceives those interests as under-recognized within the alliance. Yet, Turkish officials remain interested in mending the rift with Washington, with reports indicating that discussions around the F-35 may surface again.

Future Implications

The ongoing S-400 dispute encapsulates a complex reality facing NATO: the challenge of maintaining unity when member states pursue divergent defense policies. The resolution of this impasse could set a precedent for how NATO allies navigate disagreements involving military procurement and sovereign decision-making.

For now, the S-400 issue remains unresolved, with Turkey’s relationship with the United States and Russia both on uncertain ground. The high cost of exclusion from the F-35 program continues to weigh heavily on Turkey’s defense aspirations, but Russia’s insistence on upholding its end-user agreement leaves little room for maneuvering. In the coming months, the stakes for Turkey’s defense partnerships—and potentially NATO’s cohesion—will continue to mount as Ankara and Washington attempt to negotiate a compromise that aligns with their national interests and regional security strategies.