Türkiye's F-35 Program Process

Türkiye's F-35 Joint Strike Fighter (JSF) Program began in 1999 when Türkiye joined as an applicant participant. The process continued with Türkiye becoming a Level III partner in the System Development and Demonstration (SDD) phase on 11 July 2002 and signing the Memorandum of Understanding for Production, Sustainment and Follow-on Development (PSFD) on 25 January 2007.

As part of this, Türkiye became a potential user of the F-35A fighter aircraft and one of the partner nations in the program’s production and supply chain. Turkish defense industry companies undertook the production of approximately 900 different components, with an initial plan to procure 100 F-35A fighter aircraft. On June 2018, ownership of the first F-35 aircraft was transferred to Türkiye, and training for Turkish pilots and maintenance personnel began in the United States.^【1】

The process entered a different phase after Türkiye signed a contract with Russia for the S-400 air defense system in 2017. The United States opposed the integration of the S-400 system with the F-35 program. In 2019, training for Turkish personnel on the F-35 was halted, Türkiye’s roles in the production chain were gradually terminated, and on 17 July 2019, it was officially announced that Türkiye had been removed from the program.^【2】

In December 2020, sanctions were imposed under the Countering America's Adversaries Through Sanctions Act (CAATSA) on the Presidency of Defense Industries (SSB) and several officials. In April 2021, Türkiye’s partnership in the program was formally terminated. The six F-35A aircraft produced on Türkiye’s behalf and whose ownership had been transferred were not delivered; it was decided that these aircraft would be purchased and allocated by the United States Air Force.

Following its removal from the F-35 program, Türkiye continued its F-16 procurement process as part of its air force modernization, initiated talks for the acquisition of Eurofighter Typhoon fighter aircraft, and continued developing its indigenous KAAN fighter aircraft project. During the same period, various diplomatic contacts were held between the two countries regarding potential solutions to the S-400 issue and the possibility of Türkiye’s re-entry into the F-35 program.

F-35 Lightning II is a fifth-generation, low-observable (stealth), single-engine, multirole fighter aircraft developed by Lockheed Martin.^【3】 The program stands out through advanced technologies such as enhanced sensor fusion, an AESA radar system, 360-degree situational awareness provided by the Distributed Aperture System (DAS), and network-centric warfare capabilities.

Under the program, three variants were developed to meet different operational needs: F-35A (conventional takeoff and landing), F-35B (short takeoff and vertical landing), and F-35C (carrier-based operations).^【4】

The F-35 Program is a multinational consortium led by the United States. Initial partners included Level I partner the United Kingdom, Level II partners Italy and the Netherlands, and Level III partners Türkiye, Canada, Australia, Norway, and Denmark.^【5】

In addition to program partners, countries such as Israel, Japan, South Korea, Belgium, Poland, Finland, Singapore, Switzerland, the Czech Republic, and Germany acquired F-35s through the United States’ Foreign Military Sales (FMS) program.

Türkiye’s participation in the F-35 Joint Strike Fighter (JSF) Program began in 1999 as an applicant participant. On 11 July 2002, Türkiye joined the System Development and Demonstration (SDD) phase as a Level III partner, becoming the seventh international partner to join the program after the United Kingdom, Italy, the Netherlands, Canada, Denmark, and Norway. Türkiye was at the same partnership level (Level III) as Canada, Denmark, and Norway; Australia became the eighth partner at the same level on 30 October 2002.

On 25 January 2007, Türkiye signed the Memorandum of Understanding for Production, Sustainment and Follow-on Development (PSFD), formally joining the production and sustainment phase of the program. Thus, Türkiye became one of the nine partners in the multinational F-35 consortium led by the United States, assuming responsibilities in both production and the supply chain.

Türkiye’s primary objective for joining the program was stated as meeting the need for a fifth-generation fighter aircraft to replace its F-16 fleet and enabling the Turkish defense industry to acquire advanced technology production capabilities. Accordingly, an initial plan was made to procure 100 F-35A fighter aircraft.

Türkiye’s initial financial contribution to the SDD phase amounted to approximately 175 million dollars, and its total financial contribution to the program over subsequent years reached approximately 1.4 billion dollars.^【6】

Türkiye issued a conditional order for the first two F-35A aircraft in January 2012, but this decision was postponed in January 2013 due to program delays and cost increases. The first firm order was placed in May 2014 by the Defense Industry Executive Committee (SSİK) under the LRIP-10 (Low Rate Initial Production) program for two aircraft in Block-3F configuration.

Six F-35A aircraft produced on Türkiye’s behalf and whose ownership had been transferred were not delivered to Türkiye.

Turkish defense industry companies contributed to the production process by manufacturing approximately 900 aircraft components under the F-35 Joint Strike Fighter Program.

The main Turkish companies contributing to the program and their areas of activity are as follows:

• TUSAŞ/TAI (Turkish Aerospace Industries Inc.): Central fuselage, central fuselage composite and metallic components.
• Alp Aviation: Components for the F135 engine, landing gear, and airframe/structural components.
• AYESAŞ: Panoramic cockpit display and missile interface unit/control cards.
• Kale Aviation: Fuselage and wing structural components; sole supplier of the landing gear uplock system for all three variants.
• Kale Pratt & Whitney: Component production for the F135 engine.
• Fokker Elmo Turkey: 40 percent of the F-35’s Electrical Wiring Interconnection System (EWIS) and central fuselage wiring; EWIS development for the F135 engine.
• Havelsan: F-35 training systems; lead Turkish organization in developing the Integrated Training Center (ITC) in Türkiye.
• Roketsan / TÜBİTAK SAGE: Development, integration, and production of the SOM-J guided munition to be carried in the F-35’s internal weapons bay.^【7】

It was projected that Turkish defense industry companies would generate approximately 9 billion dollars in production and business volume under the program.

The first aircraft delivery under the F-35 Project took place on 21 June 2018 at a formal ceremony held at the Lockheed Martin facility in Fort Worth, Texas, USA.

The first F-35 aircraft delivered with tail number 18-0001 was assigned to Luke Air Force Base in Arizona for pilot training. At the ceremony, Deputy Undersecretary of Defense Serdar Demirel, Lockheed Martin President and CEO Marillyn Hewson, and Chief of General Staff Planning Principles Directorate General Reha Ufuk Er delivered speeches.^【8】

It was announced that the second aircraft would be delivered shortly after, and the third and fourth aircraft were planned for delivery in March 2019. It was stated that during the training period for Turkish pilots, these aircraft would remain in the United States, while the fifth and sixth aircraft, scheduled for delivery to Türkiye, were expected to be delivered after completion of their production.

By the end of 2018, ownership of four F-35A aircraft had been transferred to Türkiye, and Turkish pilots and maintenance technicians underwent training programs in the United States. This number increased to six before the removal process began.

An agreement for the acquisition of the S-400 air defense system between Türkiye and Russia was signed in 2017. This agreement emerged as a result of Türkiye’s long-term air defense procurement process.

During this process, the United States and its allies urged Türkiye to purchase the Patriot air defense system compatible with NATO, but negotiations failed to reach an agreement due to Türkiye’s expectations regarding technology transfer and joint production.

The U.S. Department of Defense raised security concerns that the S-400 system was technically incompatible with NATO defense infrastructure and that Russia could gain access to NATO air defense data. Pentagon officials stated that the presence of Russian engineers during the system’s installation and maintenance in Türkiye posed a risk. The U.S. Department of Defense claimed that the deployment of the S-400 system in Türkiye could enable Russia to gather intelligence on the technical capabilities of the F-35 system.^【9】

After the completion of the S-400 agreement between Türkiye and Russia, the U.S. Congress and administration began discussing potential sanctions against Türkiye. The CAATSA (Countering America's Adversaries Through Sanctions Act), enacted in 2017, targeted primarily Russia, Iran, and North Korea, but also established a framework for imposing sanctions on third-party countries engaging in significant financial transactions with Russia’s defense sector.^【10】

The idea of blocking F-35 fighter aircraft sales to Türkiye entered the congressional agenda in 2017. David Cicilline, a member of the U.S. House of Representatives Committee on Foreign Affairs, proposed during President Erdoğan’s visit to the United States on 7 July 2017 that a provision restricting F-35 sales to Türkiye be added to the National Defense Authorization Act (NDAA) for 2018.^【11】

Under the National Defense Authorization Act for fiscal year 2019 prepared by Congress, the delivery of F-35 fighter aircraft to Türkiye was made conditional on specific requirements. As part of the regulation enacted at the end of 2018, the U.S. Department of Defense was also required to submit a comprehensive report on Türkiye’s defense relations and the risks posed by the S-400 procurement.

As the delivery of the S-400 air defense system to Türkiye approached, the U.S. administration began implementing gradual measures. According to information reported in the media on 1 April 2019 and later confirmed by the U.S. Department of Defense, training for Turkish personnel on the F-35 was halted, and some planned deliveries of materials and equipment under the program were suspended.

On 6 June 2019, U.S. Deputy Secretary of Defense Patrick Shanahan informed Türkiye’s Minister of National Defense Hulusi Akar in a letter that the training of Turkish personnel in the F-35 program had been terminated. Accordingly, Turkish personnel continuing their training at Luke Air Force Base in Arizona and Eglin Air Force Base in Florida were required to leave the facilities by 31 July 2019. As a result, the training of 42 Turkish personnel was terminated.

Ellen Lord, Undersecretary of Defense for Acquisition and Sustainment at the U.S. Department of Defense, defended the suspension of Türkiye’s partnership in the F-35 program as a “highly disciplined and phased transition” in a statement on 7 June 2019.^【12】 The same statement indicated that Turkish companies in the F-35 production chain would not be assigned new tasks and that their roles would be gradually terminated.

The Russian-made S-400 air defense system was delivered to Türkiye as planned on 12 July 2019. Following this development, on 17 July 2019, the White House announced that Türkiye had been officially removed from the F-35 program.^【13】

The White House’s official statement included the following: "Türkiye’s decision to purchase the S-400 air defense system from Russia makes its participation in the F-35 program impossible."^【14】

In a statement following a Cabinet meeting on 16 July 2019, U.S. President Donald Trump acknowledged positive relations between Türkiye and the United States but stated that "the current situation presents a contradictory picture." Trump said, "We are in a situation where Türkiye is doing very well with us, and now we are telling Türkiye, since you have been forced to acquire another missile system, we will not sell you F-35 fighter aircraft."

Trump attributed responsibility for the situation to the previous U.S. administration, stating that the refusal to allow the sale of Patriot missile systems to Türkiye during the Barack Obama administration had triggered this process. Trump added, "When they learned they would have to buy missiles, it became clear they would almost immediately start buying a similar missile from Russia, and suddenly everyone started saying to Türkiye, 'Okay, we’ll sell you the Patriot missile.'"

Trump further noted that Türkiye had signed an agreement with Russia and made substantial payments, adding, "But by that time, Türkiye had already signed an agreement with Russia for a missile system we did not allow them to buy and paid a lot of money. That was not smart. Because Türkiye is a NATO member."

The official notification of Türkiye’s removal from the program was delivered by the U.S. Department of Defense to Ankara in April 2021. The notification stated that the Memorandum of Understanding signed in 2006 and ratified by Türkiye on 26 January 2007 had been terminated and that Türkiye was no longer included in the updated agreement text.

After Türkiye’s removal from the F-35 program, the six F-35 aircraft whose ownership had been transferred to Türkiye were not transferred and were instead allocated to the United States Air Force under the 2020 defense budget.

The U.S. Department of the Treasury, in December 2020, included the Presidency of Defense Industries (SSB) of the Republic of Türkiye and SSB President İsmail Demir, along with senior officials Mustafa Alper Deniz, Serhat Gençoğlu, and Faruk Yiğit, on the sanctions list under Section 231 of CAATSA.

The restrictions imposed on SSB under these sanctions are as follows:

• Denial of export licenses and authorizations for U.S.-origin products and technologies;
• Prohibition of SSB from obtaining credit or loans exceeding 10 million dollars with a 12-month maturity from U.S. financial institutions;
• Prevention of SSB from obtaining credit or loans from international financial institutions;
• Ban on entry into the United States for the sanctioned officials.

CAATSA sanctions marked the first application of secondary sanctions and the first CAATSA sanctions imposed on a NATO member country.^【15】

U.S. President Donald Trump implemented the CAATSA sanctions based on the 2020 National Defense Authorization Act and before signing the 2021 NDAA law.

Section 1245 of the U.S. National Defense Authorization Act (NDAA) for fiscal year 2020 permanently prohibited the sale of F-35 fighter aircraft to Türkiye, with the lifting of this ban conditional on three requirements: (1) Türkiye does not retain any S-400 system equipment on its territory, (2) no further S-400 deliveries are made to Türkiye, and (3) the S-400 procurement does not compromise sensitive information related to the F-35 system.

Numerous legislative proposals against Türkiye were submitted to the U.S. Congress, but the majority failed to pass. In contrast, measures preventing the delivery of F-35 aircraft to Türkiye were adopted as part of annual defense budget laws (NDAA), rather than as independent legislation.

Following Türkiye’s removal from the F-35 Program, alternative procurement options for modernizing the Turkish Air Force became a priority. In this context, various fighter aircraft platforms, including the Eurofighter Typhoon, were evaluated, and the development of the indigenous KAAN project was accelerated.

In September 2022, President Recep Tayyip Erdoğan, in his assessment of the F-16 procurement process, stated, "The United States is not the only country in the world selling fighter aircraft. The United Kingdom, France, and Russia also sell them." ^【16】 During the same period, then Presidential Spokesperson Ibrahim Kalın stated that Türkiye had conducted negotiations with European countries regarding the acquisition of Eurofighter Typhoon fighter aircraft and emphasized that Türkiye had no alternative in terms of its defense needs.

In November 2023, Minister of National Defense Yaşar Güler stated during discussions in the TBMM Planning and Budget Committee that Türkiye intended to procure the Eurofighter Typhoon. As negotiations on the Eurofighter continued, President Erdoğan affirmed that Türkiye was continuing to evaluate other fighter aircraft options.

Türkiye’s efforts to procure the Eurofighter Typhoon progressed following negotiations with the United Kingdom and other Eurofighter consortium member countries from 2023 onward. On 27 October 2025, President Recep Tayyip Erdoğan and United Kingdom Prime Minister Keir Starmer signed the Türkiye–United Kingdom Eurofighter Typhoon Cooperation Agreement in Ankara.

The agreement covers the procurement process of Eurofighter Typhoon fighter aircraft, technical cooperation, maintenance and sustainment activities, and joint defense industry collaboration. Under the agreement, the United Kingdom is expected to provide 20 Eurofighter Typhoon fighter aircraft to Türkiye in the initial phase, with additional procurement options to be evaluated in subsequent stages.

KAAN, formerly known as the National Combat Aircraft (MMU), is a national defense industry project undertaken by Türkiye to develop a fifth-generation fighter aircraft. The project is led by Turkish Aerospace Industries Inc. (TUSAŞ), coordinated by the Presidency of Defense Industries (SSB), and supported by domestic defense industry institutions. The primary goal of the program is to develop a domestic fighter aircraft to replace the F-16 fleet in the inventory of the Turkish Air Force.

The KAAN prototype conducted its first flight on 21 February 2024 at the Mürted Air Base Command in Ankara. During the approximately 13-minute flight, the aircraft reached an altitude of 8,000 feet and a speed of 230 knots. The second test flight was conducted on 6 May 2024, during which the aircraft remained airborne for approximately 14 minutes, reaching an altitude of 10,000 feet and a speed of 230 knots.

KAAN is being developed as a twin-engine, multirole, low-observable (stealth), and network-enabled fifth-generation fighter aircraft. Design objectives include sensor fusion, AESA radar, electronic warfare systems, internal weapons bays, digital cockpit, open architecture, wide-area display system, helmet-mounted display system, and AI-assisted mission systems.

Digital twin technology is being used in the program; structural, mechanical, and electronic components of the aircraft are modeled and tested in a digital environment. Additionally, radar cross-section testing and development of various critical subsystems are being conducted with contributions from TÜBİTAK BİLGEM and other domestic defense industry institutions.

Initial prototypes use General Electric F110 turbofan engines. In the long term, the program aims to integrate a domestically developed engine by TEI.

TUSAŞ has set design targets for KAAN, including a length of approximately 21 meters, a wingspan of 14 meters, a maximum speed of Mach 1.8, and a service ceiling of 55,000 feet. The aircraft is being developed to perform both air-to-air and air-to-ground missions.

On 11 June 2025, a government-to-government supply agreement for the export of 48 KAAN fighter aircraft was signed between Türkiye and Indonesia. The commercial contract for the agreement was signed on 26 July 2025 during the 17th International Defense Industry Fair (IDEF 2025).

After the delivery of the S-400 air defense system to Türkiye, whether the system would be activated became central to negotiations. U.S. Secretary of State Mike Pompeo and Republican Senator Lindsey Graham stated that if the S-400 systems were not activated, Türkiye could be exempted from CAATSA sanctions and reconsidered for re-entry into the F-35 program.

In contrast, U.S. Secretary of Defense Mark Esper rejected this approach, stating, "It’s either the S-400 or the F-35. It cannot be one in the garage and the other outside."

John Kirby, Strategic Communications Coordinator at the White House National Security Council, responded to the question of F-35 program re-entry following the sale of F-16s to Türkiye in a daily press briefing in January 2024: "Our discussions on this matter are ongoing; if Türkiye can address our concerns, then its participation in the F-35 program can be restored."^【17】

During the same period, Acting Deputy Secretary of State Victoria Nuland, during her meetings in Türkiye, stated that the United States would welcome Türkiye’s re-entry into the F-35 program if the issue regarding the S-400 system were resolved.

U.S. Ambassador to Ankara and Special Envoy to Syria Tom Barrack, during a conference organized by the Milken Institute in the United Arab Emirates in December 2025, provided an assessment of negotiations between the United States and Türkiye. Regarding the bilateral meeting between Trump and President Erdoğan at the White House, Barrack said: "President Trump and President Erdoğan held a bilateral meeting at the White House. That was a great thing. There were six important issues on the agenda that had been pending for ten years, and they resolved most of them, including the two conditions regarding the S-400. Operationalization, which they resolved, and ownership, which is a bit more difficult. All of these are in negotiation. I believe these issues will be resolved in the next four to six months, and relations will move to the next stage." These relations are strong and good. Everyone is fulfilling their obligations."^【18】

Barrack also emphasized in the same speech that Türkiye was an important part of the F-35 program, noting that four F-35s were waiting in storage but inaccessible, and that U.S. President Donald Trump found the sanctions against Türkiye "meaningless."