Turkey’s Bid to Rejoin F-35 Program Faces Fierce US Opposition Amid S-400, Hamas and NATO Security Fears

(DEFENCE SECURITY ASIA) — The United States Congress has ignited a new front in its long-running standoff with Ankara, as bipartisan lawmakers intensify efforts to permanently block Turkey from rejoining the F-35 Joint Strike Fighter program, citing national security risks, Russian entanglements, and growing concerns over President Recep Tayyip Erdogan’s open support for Hamas.

The battle over Turkey’s reinstatement has become one of the most explosive defence disputes inside NATO, striking at the very core of alliance trust and raising urgent questions about whether the United States can shield its most advanced fifth-generation stealth fighter from adversarial exploitation.

At the centre of this storm is the F-35 Lightning II, Lockheed Martin’s crown jewel of modern aerial warfare, designed with radar-evading stealth, sensor fusion, and unmatched network-enabled combat capability.

Turkey was once a founding partner in the trillion-dollar program, investing heavily in production lines and committing to procure more than 100 aircraft.

But its purchase of the Russian-made S-400 “Triumf” air defence system in 2019 triggered alarm in Washington, where defence officials argued that Moscow could exploit the system’s radar to harvest critical data on the F-35’s stealth profile.

The United States responded by expelling Turkey from the program, halting pilot training, suspending jet deliveries, and imposing sweeping sanctions on its defence industry under the Countering America’s Adversaries Through Sanctions Act (CAATSA).

Despite immense pressure, Ankara has refused to dismantle the S-400, insisting instead on its sovereign right to pursue “diverse defence partnerships” — a position that has hardened opposition in Washington.

Tensions briefly appeared to ease when Washington approved a $23 billion F-16 Block 70/72 deal for Turkey in early 2025, but lawmakers made clear that the advanced stealth fighter remained firmly off limits.

Israel, a key F-35 operator in the Middle East, has quietly but forcefully lobbied Congress to block any return, citing Erdogan’s unpredictable policies and direct support for Hamas as existential threats to its national security.

 

Ankara’s Alternative Path: KAAN and the Eurofighter Typhoon

With its F-35 ambitions increasingly uncertain, Ankara has accelerated parallel efforts to secure next-generation combat capabilities.

In 2023, Türkiye unveiled its indigenous KAAN fifth-generation fighter, developed by Turkish Aerospace Industries, positioning it as a direct competitor to the F-35, J-35, and South Korea’s KF-21 Boramae.

KAAN, designed with stealth shaping, advanced avionics, and integration of indigenous weapons, is expected to enter flight testing in the second half of this decade, though Western analysts caution that timelines may slip due to engine and systems integration challenges.

Simultaneously, Türkiye has moved to bolster its interim capabilities by finalising the procurement of 40 Eurofighter Typhoon multirole fighters, negotiated with the UK, Spain, Germany, and Italy.

The Typhoon deal is seen as a stopgap solution to modernise the Turkish Air Force while Ankara advances its KAAN program, bridging a potential capability gap as its F-16 fleet ages.

Defence experts note that if excluded permanently from the F-35 program, Ankara’s combined investment in KAAN and Eurofighter will reshape its aerospace trajectory, reducing dependence on US platforms while embedding deeper ties with European and indigenous systems.

KAAN: Turkiye’s Fifth-Generation Stealth Fighter Aiming to Rival the F-35

Turkiye’s KAAN stealth fighter marks the country’s boldest leap into fifth-generation aviation, intended not only to modernise its own air force but also to challenge Western dominance in the global fighter market.

Measuring 21 meters in length with a 14-meter wingspan, KAAN has been designed with radar-deflecting contours and internal weapon bays, underscoring Turkiye’s ambition to rival established platforms such as the American F-35 and China’s J-35.

Its projected top speed of Mach 1.8 and supersonic endurance reflect a design emphasis on both air-superiority missions and deep-strike penetration in contested environments.

With a combat radius estimated at 1,100 kilometres, KAAN could give Ankara the ability to project power across the Eastern Mediterranean, the Black Sea, and even into the Middle East without relying heavily on tanker support.

The twin-engine configuration provides redundancy and higher thrust, with Turkiye planning to transition from imported powerplants to an indigenous TRMotor engine, a move that would reduce strategic dependence on foreign suppliers.

Its Gallium Nitride-based AESA radar promises high detection ranges, multi-target engagement, and resistance to advanced jamming, offering survivability against modern Russian and Chinese air-defence networks.

Beyond avionics, KAAN will feature sensor fusion, helmet-mounted cueing, and an electronic warfare suite designed to outmatch legacy aircraft and operate seamlessly in complex multi-domain battlespaces.

The fighter is expected to carry up to 10 tons of ordnance, including indigenous beyond-visual-range missiles, precision-guided bombs, and standoff munitions, positioning Turkiye as both a developer and exporter of advanced weapons.

Stealth is further reinforced by the internal weapons bay, enabling KAAN to maintain a low radar cross-section while prosecuting strikes against defended targets.

Scheduled for full operational capability in the early 2030s, KAAN symbolises Turkiye’s strategic pivot toward self-sufficiency and positions it as a potential disruptor in the fifth-generation fighter export market, especially among nations denied access to the F-35.

A Bipartisan Line in the Sand

On August 8, 2025, the Congressional Hellenic Caucus delivered a thunderous blow to Ankara’s ambitions.

Forty House members, led by Reps. Chris Pappas (D-NH), Gus Bilirakis (R-FL), Dina Titus (D-NV), and Nicole Malliotakis (R-NY), signed a letter to Secretary of State Marco Rubio demanding that Turkey’s request be flatly rejected.

“We urge you to uphold US law, maintain the sanctions levied under CAATSA, and reject Turkey’s request to rejoin the F-35 program,” the lawmakers wrote.

The letter argued that reinstatement would “jeopardize the integrity of F-35 systems,” expose NATO’s most critical aircraft to Russian intelligence gathering, undermine allied trust in US technology, and derail future sixth-generation fighter cooperation programs such as the NGAD and the Global Combat Air Programme.

The campaign has won the backing of powerful advocacy groups, including the American Jewish Committee, the American Hellenic Institute, the Armenian National Committee of America, and Christians United for Israel Action Fund.

The alignment of Greek, Armenian, Jewish, and Kurdish lobbying groups underscores how Turkey’s regional assertiveness — from airspace violations over the Aegean to its entrenched occupation of northern Cyprus — has converged into a rare bipartisan consensus in Washington.

Hamas, Russia, and New Legislative Firewalls

The campaign escalated dramatically on September 8, 2025, when Israeli daily Maariv revealed that US lawmakers are pushing new amendments to the 2026 National Defense Authorization Act (NDAA) aimed at locking Turkey out of US defence technology unless Ankara meets unprecedented conditions.

One amendment, championed by Reps. Bilirakis and Brad Schneider (D-IL), explicitly prohibits F-35 sales unless the White House certifies that Turkey does not “substantially support Hamas or any of its factions,” poses no military threat to Israel, and halts cooperation with Russia, China, Iran, or North Korea.

The legislation also calls for direct investigations into Hamas leadership networks operating openly in Turkey, where senior officials have been hosted by Erdogan under the guise of “political resistance.”

Critics warn that Ankara’s growing defence cooperation with Russia — including drone sales, energy partnerships, and strategic consultations over Syria and the Caucasus — directly undermines NATO security architecture.

Senator James Risch (R-ID) has already vowed to indefinitely block any F-35 transfer, signalling that the momentum is shifting toward a permanent embargo.

Social media commentary has amplified the issue, with security analysts highlighting the dangerous paradox of a NATO member simultaneously hosting Hamas leaders, operating Russian air defence systems, and seeking access to the alliance’s most advanced stealth aircraft.

Erdogan’s Calculus and the Future of NATO

Erdogan has brushed aside congressional anger, accusing Washington of hypocrisy and declaring that “Turkey cannot be treated as a second-class ally.”

Yet analysts caution that Ankara’s insistence on retaining the S-400 while simultaneously courting access to NATO’s most sensitive platform reflects a deliberate gamble.

For Erdogan, the F-35 is more than an aircraft — it represents a pathway to modernising the Turkish Air Force beyond its ageing F-16 fleet and cementing Ankara’s place as a global aerospace power.

With the KAAN project and Eurofighter deal, Erdogan is signalling that Türkiye will not allow its aerial ambitions to be dictated solely by Washington’s approval or denial.

If permanently blocked, Turkey may deepen cooperation with Russia and China or leverage KAAN and Eurofighter to sustain its military edge, reshaping the balance of power in the Middle East and Eastern Mediterranean.

Defence experts warn that Turkey’s pivot could also fracture NATO’s Black Sea security strategy, complicating efforts to contain Russia’s naval operations and sustain Ukraine’s war effort.

Mark Dubowitz of the Foundation for Defense of Democracies bluntly argued: “Rewarding Turkey’s behaviour risks US interests. The price of alliance unity cannot be the surrender of America’s crown jewel to Russian exploitation.”

The Strategic Stakes

The F-35 debate is ultimately a stress test of NATO’s capacity to police technology security inside the alliance when a member’s external alignments collide with collective defence imperatives.

At the core is a fundamentals question of emissions security and counter-intelligence hygiene: can a NATO air arm operate a fifth-generation stealth fleet while simultaneously fielding a Russian S-400 ecosystem that is engineered to learn, catalogue, and iteratively refine signatures against exactly those aircraft.

For Washington, the issue is less about punishing Ankara and more about preserving the sanctity of a platform whose survivability depends on the opacity of its radar cross section, mission-data files, electronic-warfare libraries, and the telemetry of its health-and-usage systems.

If that opacity is compromised, even probabilistically, the risk propagates to every allied operator from Israel’s squadron over the Levant to Japan’s F-35s postured against China and North Korea, because a vulnerability discovered in one fleet can be scaled across the global enterprise.

Sanctions credibility under CAATSA is also on trial, because any carve-out for a NATO state that refuses to divest a sanctioned Russian system signals to partners and adversaries alike that statutory red lines are negotiable when geopolitics get messy.

Undermining sanctions cohesion would not only embolden Moscow’s defence exports but also complicate US efforts to corral third countries on Iran-, DPRK-, and PRC-linked proliferation where supply chains are already fragmented and grey-market dependent.

Interoperability is another underappreciated centre of gravity, since the F-35 is a networked sensor-shooter whose value multiplies through common data standards, sovereign mission-data reprogramming, and secure logistics clouds rather than through the airframe alone.

Admitting a persistent S-400 operator back into the F-35 club risks forcing balkanised tactics, non-standard emission control rules, and data-diode workarounds that degrade the very coalition synergies the jet was built to unlock.

The downstream effect is strategic: fractured interoperability drives allies toward parallel development paths, which raises programmatic cost curves for sixth-generation efforts like NGAD, GCAP, and Europe’s FCAS while handing time and maneuver space to peer adversaries.

Arms sales conditionality has therefore become an instrument of alliance discipline, functioning not simply as commercial policy but as technology-protection strategy with direct implications for order-of-battle credibility in the Eastern Mediterranean, Black Sea, and Red Sea theatres.

In the Black Sea, where NATO’s air and maritime posture must absorb Russian strike, air-defence, and electronic-warfare complexes, any compromise to fifth-gen signatures or TTPs could diminish stand-in strike options and increase tanker, AWACS, and P-8 vulnerability across the sustainment chain.

In the Eastern Mediterranean, where gas infrastructure, maritime boundary disputes, and Syria-Lebanon air corridors intersect, diluted F-35 confidentiality would ripple into campaign planning for standoff munitions, SEAD/DEAD sequencing, and cross-domain deconfliction with naval Tomahawk and submarine-launched effects.

The question also intersects with Europe’s rearmament cycle, because a permissive readmission would incentivise hedging behaviours in other capitals—purchasing non-NATO air-defence kits or dual-use sensors—while still seeking access to protected Western airframes and precision weapons.

That dynamic raises end-use monitoring burdens for the United States, stretching programs like Blue Lantern and Golden Sentry and complicating ITAR compliance at a time when rapid surge approvals are needed to sustain Ukraine and deter in the Indo-Pacific.

For Türkiye specifically, permanent exclusion accelerates a structural pivot toward a mixed fleet strategy anchored by the indigenous KAAN program and a European bridge via the Eurofighter Typhoon, which together would reduce US leverage over Ankara’s aerospace trajectory.

A KAAN-Typhoon pathway, if paired with deeper industrial localisation and third-party collaboration, could deliver respectable multi-domain effects for the Turkish Air Force by the early 2030s, even if it lacks the holistic low-observable ecosystem, software cadence, and coalition plug-and-play that define the F-35.

Such a pivot would alter procurement diplomacy across the Middle East and Central Asia, as Ankara markets KAAN-adjacent avionics, weapons, and MRO packages to states seeking alternatives to US export conditionality, thereby reshaping regional defence supply chains.

Conversely, a conditional pathway back into the F-35—predicated on verifiable S-400 divestment and durable compliance mechanisms—would reaffirm the norm that access to crown-jewel capabilities requires airtight alignment on counter-intelligence and technology-protection practices.

The NDAA debate therefore becomes a proxy referendum on how the United States balances alliance management with platform sanctity: a permissive decision risks eroding trust in the F-35 enterprise, while a restrictive decision could push a pivotal NATO ally further toward strategic non-alignment.

In an era of great-power rivalry defined by data advantage, electronic warfare supremacy, and supply-chain resilience, the outcome will shape not only which aircraft Ankara flies but how credible NATO looks when it claims to defend both its borders and its most sensitive technologies. — DEFENCE SECURITY ASIA