F-35 Lightning II: Turkey’s Potential Return and NATO Airpower Stakes
Few geopolitical puzzles are as layered — or as consequential — as the question of whether Turkey will ever fly the F-35 Lightning II. What began as a flagship partnership between Ankara and Washington in one of the most ambitious defense programs in history collapsed in dramatic fashion when Turkey chose a Russian missile system over Allied solidarity. Five years later, the wreckage of that decision still shapes the strategic landscape of the Eastern Mediterranean, the Black Sea, and NATO’s southern flank.
The renewed momentum behind Turkey’s potential return to the F-35 program isn’t just about fighter jets. It’s about trust, leverage, and the uncomfortable reality that NATO needs Turkey as much as Turkey needs NATO. With Greece receiving F-35s, Russia pressing on Ukraine’s borders, and Turkey’s own indigenous fighter jet program racing toward operational readiness, the window for diplomatic resolution may be narrower than anyone in Washington or Ankara wants to admit.
This article maps the full picture — from the origins of the rift to the real conditions for reintegration, the regional power shifts at stake, and what Turkey’s return (or permanent exclusion) would mean for the future of collective Western defense.
The Genesis of the Rift: How Turkey Lost Its F-35
A Founding Partner Turned Adversary
Turkey wasn’t just a customer for the F-35 — it was a builder. As a Level 3 partner in the Joint Strike Fighter (JSF) program, Turkish aerospace companies manufactured over 900 individual parts for the aircraft, including critical components like fuselage center sections and landing gear assemblies. Ankara had committed to purchasing 100 F-35A jets and had invested approximately $1.4 billion into the program by the time the relationship fell apart.
That industrial footprint made Turkey’s expulsion logistically painful for everyone involved. The Pentagon had to scramble to identify replacement suppliers for Turkish-made components — a process that cost time, money, and production momentum for a program already notorious for delays and cost overruns.
The S-400 Decision: Why Turkey Chose Russia
To understand why Turkey purchased the Russian S-400 Triumf air defense system, you have to understand Ankara’s security calculus in the mid-2010s. Turkey had spent years attempting to procure a modern long-range air defense capability through NATO channels, including a failed bid for the Patriot system in 2013 that collapsed partly over technology transfer demands.
Facing a deteriorating security environment — ISIS to the south, Kurdish militant groups along its borders, and growing instability across the region — Turkey turned to Russia’s offer of the S-400 in 2017. Moscow sweetened the deal with co-production agreements and a price tag Turkey found competitive. Deliveries began in July 2019.
Washington’s objections were specific and serious. US defense officials argued that operating the S-400 alongside F-35s would allow Russian sensors to map the stealth aircraft’s radar cross-section and electronic signature — essentially giving Moscow a free intelligence windfall on NATO’s most advanced fighter. The concern wasn’t theoretical; it was rooted in how the S-400’s acquisition radar system works. There was also the broader issue of interoperability: NATO’s integrated air defense network wasn’t built to incorporate Russian hardware.
The Formal Expulsion and CAATSA Sanctions
The US officially removed Turkey from the F-35 program in July 2019, the same month the first S-400 components arrived on Turkish soil. The move was both punitive and preventive. Then, in December 2020, the Trump administration imposed sanctions under the Countering America’s Adversaries Through Sanctions Act (CAATSA), targeting Turkey’s Presidency of Defense Industries (SSB) and its director, İsmail Demir.
Those sanctions were the first time CAATSA had been applied to a NATO ally — a signal of how seriously Washington viewed the transgression. The $1.4 billion Turkey had paid into the F-35 program was earmarked to offset the cost of replacing Turkish-made parts in the supply chain, rather than returned as a refund.
The Path to Potential Return: Diplomacy, Deals, and Obstacles
How the F-16 Deal Changed the Equation
The diplomatic thaw began not with F-35 discussions but with a more modest ask. Turkey formally requested 40 new F-16 Block 70 fighter jets and 79 modernization kits for its existing fleet — a package valued at $23 billion. For years, Congressional opposition held the deal hostage, with critics citing Turkey’s human rights record, its delayed ratification of Finland and Sweden’s NATO bids, and the unresolved S-400 issue.
The calculus shifted when Turkey ratified Sweden’s NATO membership in January 2024, removing the final political barrier that had prolonged the F-16 negotiations. Congress subsequently approved the sale — a significant diplomatic win for Ankara and a clear signal that good-faith gestures would be rewarded. Many analysts now view the F-16 deal as the opening chapter of a longer reintegration story with the F-35 as the next, far more complex, volume.
US Lawmakers Signal Openness
Perhaps the most notable indicator of shifting sentiment came from US senators who had previously been among the loudest critics of Turkey’s military posture. Senators including Lindsey Graham and Jeanne Shaheen have expressed openness to discussing Turkey’s potential return to the F-35 program, framing it as a strategic necessity rather than a concession. Their position reflects a pragmatic recognition: a NATO ally flying aging F-16s while adversaries modernize is a liability no alliance can afford indefinitely.
The S-400 Conundrum: More Than a Simple Yes or No
Here’s where the diplomatic path gets genuinely complicated. The United States has consistently maintained that Turkey must resolve the S-400 issue before any F-35 discussions can progress meaningfully. But “resolving” the S-400 isn’t as straightforward as it sounds.
Outright divestment — selling or destroying the system — would be politically explosive for President Erdoğan domestically. Turkey paid an estimated $2.5 billion for the system, and abandoning it would be framed by political opponents as a humiliating capitulation to Western pressure.
Verifiable deactivation presents a middle path that some diplomatic circles have quietly explored. Under this scenario, Turkey would commit to keeping the S-400 in storage, with no operational integration into its air defense network, and would allow verification mechanisms to confirm compliance. The challenge is that US defense officials remain skeptical that deactivation alone eliminates the intelligence risk — particularly if the system’s data collection components remain intact.
A third option involves third-party transfer — selling or donating the S-400s to a country outside NATO, potentially Ukraine, as has been suggested in some policy circles. Kyiv would benefit from additional air defense capability, and Turkey would shed its most significant diplomatic liability. Whether Moscow would tolerate such a move without consequences is another matter entirely.
Beyond the S-400: The Implicit Conditions
American policymakers aren’t just focused on the hardware. Rebuilding trust with Ankara requires addressing a broader set of concerns that include guarantees against future purchases of Russian defense systems, Turkey’s commitment to democratic governance standards, and a demonstrated pattern of alignment with NATO’s collective security interests rather than strategic ambiguity.
These implicit conditions are harder to codify than a specific demand about a missile system — and harder for any Turkish government to publicly accept without domestic backlash. Navigating that tension will require sustained, quiet diplomacy rather than high-profile ultimatums.
The Stakes for NATO Airpower and Regional Stability
Turkey’s Strategic Weight Within the Alliance
Turkey’s geographic position gives it military significance that no other NATO ally can replicate. It controls the Turkish Straits — the only maritime route between the Black Sea and the Mediterranean — and shares borders with eight countries, including Russia’s regional partner Georgia and NATO’s restive southern neighbors. Turkey also hosts the Incirlik Air Base, a critical hub for US and NATO air operations.
An F-35-equipped Turkey would dramatically strengthen NATO’s coverage of the Black Sea region, where Russia’s Black Sea Fleet has operated with relative freedom of movement. The F-35’s advanced sensor fusion, low-observable profile, and long-range strike capability would give NATO commanders tools that no current Turkish aircraft can provide. In a region where Russian Su-35s and S-400 systems define the threat environment, fifth-generation capability isn’t a luxury — it’s a strategic requirement.
The Eastern Mediterranean Balance Sheet
Turkey’s potential F-35 acquisition doesn’t exist in a vacuum. Greece formally requested 20 F-35A fighter jets in 2022, with deliveries expected from 2028 onward. Athens has positioned this acquisition as a response to Turkey’s military modernization — a dynamic that illustrates both the alliance’s internal tensions and the arms competition simmering beneath NATO’s unity messaging.
If Greece fields F-35s while Turkey continues flying upgraded F-16s, the aerial balance between two NATO allies shifts in ways that could embolden Greek strategic assertiveness and deepen Turkish frustration. Paradoxically, bringing Turkey back into the F-35 program might actually reduce intra-alliance friction by restoring a rough equilibrium between the two rivals — a point that NATO planners quietly acknowledge.
Israel’s equation is equally complex. Israel operates F-35I Adir variants, customized versions of the F-35A with Israeli-specific modifications and electronic warfare systems. Tel Aviv has historically relied on its qualitative military edge in the region, and Israeli defense officials have expressed concern about the prospect of neighboring states acquiring comparable platforms. A Turkish F-35 fleet would require careful diplomatic management to prevent it from destabilizing the security architecture that underpins US commitments to Israel.
Russia’s Calculus and the Black Sea Dimension
From Moscow’s perspective, a Turkey armed with F-35s represents a genuine strategic setback — which is precisely why Russian officials have repeatedly warned Ankara against abandoning the S-400 or moving closer to Washington. Russia’s investment in the S-400 sale was never purely commercial; it was designed to create exactly the kind of Western-Turkey friction that has persisted for five years. Resolving it on terms favorable to NATO would constitute a significant defeat for Russian influence operations in the alliance’s southern tier.
Turkey’s Strategic Calculus and the KAAN Factor
Why Ankara Needs Fifth-Generation Capability
Turkey’s F-16 fleet, while capable, is aging. Many of the aircraft entered service in the 1990s, and even with modernization kits, they face growing challenges from the advanced integrated air defense systems proliferating across the region. Syria operates Russian-supplied air defenses. Iran’s military continues to develop its capabilities. And Greece’s pending F-35 acquisition eliminates Turkey’s longstanding qualitative edge in the Aegean.
Turkey’s military planners are acutely aware that fourth-generation fighters — no matter how well upgraded — operate at a fundamental disadvantage against fifth-generation platforms and modern air defense networks in contested airspace. The F-35’s combination of stealth, sensor fusion, and electronic warfare capability isn’t just incrementally better; it represents a different category of air combat altogether.
The KAAN Indigenous Fighter: Leverage or Lifeline?
Turkey’s response to its F-35 exclusion wasn’t just diplomatic frustration — it was industrial acceleration. The TF-X KAAN program, Turkey’s indigenous fifth-generation fighter development, made its maiden flight in February 2024, a milestone that generated significant national pride and international attention.
KAAN’s prototype flight demonstrated that Turkey possesses genuine aerospace engineering ambition. But ambition and operational capability are separated by years of difficult development work. The aircraft still lacks a domestic engine — a critical gap that Turkey has struggled to fill, currently relying on General Electric F110 engines for the prototype. Developing a domestic powerplant with the thrust and reliability needed for a frontline combat aircraft is a decade-long undertaking at minimum.
Stealth coatings, advanced avionics integration, electronic warfare systems, and beyond-visual-range missile compatibility all require technologies that Turkey has not yet fully mastered. Most independent analysts project that a fully operational KAAN fleet — if the program stays on track — wouldn’t be available in meaningful numbers until the late 2030s at the earliest.
This timeline creates a critical strategic window. Turkey needs advanced airpower now or in the near-term future, not in fifteen years. KAAN gives Ankara leverage in negotiations — the implicit message that if the F-35 door remains closed, Turkey will build its own — but it doesn’t eliminate the urgency of finding a near-term solution.
What Turkey Lost Economically
The financial cost of F-35 exclusion extends beyond the $1.4 billion already paid into the program. Turkish aerospace companies that were producing F-35 components lost long-term manufacturing contracts worth hundreds of millions of dollars annually. Firms like Alp Aviation, Ayesas, and Roketsan had invested in tooling, training, and production capacity specifically for F-35 work — investments that became stranded assets overnight.
Reintegration into the F-35 supply chain would restore those contracts and signal to the global defense market that Turkish aerospace companies are reliable long-term partners. That reputational dimension matters as Turkey attempts to grow its defense export industry, which has expanded significantly over the past decade through programs like the Bayraktar TB2 drone.
Challenges and Roadblocks That Won’t Disappear Overnight
Congressional Opposition Remains Real
Even with improved diplomatic signals, the US Congress contains influential voices who remain skeptical of any rapid reintegration. Members of the House Armed Services Committee and the Senate Foreign Relations Committee have raised concerns that extend beyond the S-400 — including Turkey’s human rights record, its purchase of Iranian oil in violation of US sanctions, and its sometimes-adversarial relationship with Kurdish forces that US special operations troops fought alongside in Syria.
These concerns don’t have technical solutions. They require sustained political capital from the executive branch and a pattern of Turkish behavior that rebuilds Congressional confidence over time. That’s a multi-year process, not a single negotiating session.
Technical Reintegration Challenges
Bringing Turkey back into the F-35 program isn’t simply a matter of flipping a switch. The industrial capacity that Turkish firms had built for F-35 component manufacturing would need to be rebuilt or verified, production contracts renegotiated, and quality control processes re-certified. For the Turkish Air Force, pilot training pipelines, ground crew certification, and base infrastructure would all require significant investment.
None of these are insurmountable obstacles, but they add cost and time to what is already a complex process. Pentagon officials have emphasized that any reintegration process would need to be gradual and conditions-based — not a single dramatic announcement but a phased program with clear benchmarks.
Regional Objections from Greece and Cyprus
Greece has watched the F-35 discussions with deep interest and some alarm. Athens has historically opposed arms sales to Turkey that it perceives as upsetting the regional balance, and Cyprus — which maintains close ties with Greece and has its own disputes with Ankara over maritime boundaries and the divided island’s status — would likely lobby EU partners against facilitating Turkey’s return.
Managing these objections without alienating Greece, another critical NATO ally with its own strategic importance in the Eastern Mediterranean, is a diplomatic balancing act that US policymakers have not yet clearly articulated how to execute.
Conclusion: A Long Road, But One Worth Walking
The F-35 Lightning II question and Turkey’s potential return to the program sits at the intersection of military hardware, great-power competition, alliance politics, and regional stability in ways that make it one of the defining defense policy questions of the 2020s. No single variable — not the S-400, not CAATSA, not Turkey’s election cycle — determines the outcome. It’s the combination of all of them, evolving simultaneously.
What’s clear is that the strategic cost of permanent exclusion is rising for everyone involved. NATO loses the coherence and capability of a fully integrated southern flank. Turkey loses access to the most capable fighter in the Western inventory while its regional competitors modernize. The United States loses the deeper alignment with a pivotal ally that it needs to manage an increasingly complex global threat environment.
The F-16 deal showed that progress is possible when political will exists on both sides. The KAAN program’s maiden flight demonstrated that Turkey isn’t simply waiting passively for Washington’s permission — it’s building its own future, even if that future is years away. And the diplomatic signals coming from both capitals, while still tentative, suggest that both sides recognize the strategic imperative of finding a way forward.
The road back for Turkey into the F-35 program will be long, technically complex, and politically contentious. But given what’s at stake — for NATO’s collective defense, for regional stability, and for the US-Turkey relationship — it’s a road that neither side can afford to abandon.
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Frequently Asked Questions
Why was Turkey removed from the F-35 program?
Turkey was formally removed from the F-35 program in July 2019 after taking delivery of the Russian S-400 Triumf air defense system. The US argued that operating S-400 sensors alongside F-35s would give Russia critical intelligence about the stealth fighter’s radar signature, creating an unacceptable security risk for the program.
How much did Turkey invest in the F-35 program before its expulsion?
Turkey had paid approximately $1.4 billion into the F-35 program. Rather than returning these funds, the US indicated the money would be used to offset the costs of finding replacement suppliers for the 900-plus components that Turkish firms had been manufacturing for the aircraft.
What is the main obstacle to Turkey rejoining the F-35 program?
The S-400 remains the primary and most concrete obstacle. The US has consistently stated that Turkey must resolve the S-400 issue — whether through divestment, verifiable deactivation, or third-party transfer — before F-35 discussions can meaningfully advance. Beyond the hardware, rebuilding broader political trust with Congress is equally important.
What is Turkey’s KAAN fighter jet, and does it replace the need for F-35s?
The KAAN (TF-X) is Turkey’s indigenous fifth-generation fighter program, which completed its maiden flight in February 2024. While it represents significant ambition, KAAN still lacks a domestic engine and faces years of development before reaching operational capability — likely not in meaningful numbers until the late 2030s. It provides Ankara with strategic leverage but doesn’t address Turkey’s near-term airpower needs.
How does Turkey’s potential F-35 acquisition affect Greece?
Greece formally requested 20 F-35A jets in 2022, with deliveries expected from 2028. If Greece receives F-35s while Turkey continues flying upgraded F-16s, the aerial balance between the two NATO rivals shifts significantly. Some analysts argue that bringing Turkey back into the F-35 program could actually reduce intra-alliance tension by restoring rough parity between Athens and Ankara.
What role did the F-16 deal play in Turkey’s potential F-35 return?
Turkey’s $23 billion request for 40 new F-16 Block 70 jets and 79 modernization kits was approved by the US Congress after Turkey ratified Sweden’s NATO membership in January 2024. Many analysts view the F-16 approval as a diplomatic stepping stone — proof that incremental confidence-building can unlock progress on the larger and more contentious F-35 question.