Trump’s promises to Erdogan made headlines, but law, Congress, and entrenched security politics still decide what actually moves An official letter sent by the US Department of State to Congress in late July set the dispute between Türkiye and the US over F-35 fighter jets back to square one.The transfer of the aircraft and Türkiye’s reinstatement in the program are still impossible because Ankara continues to possess the Russian-made S-400 air defense system and associated equipment, has not provided legally sufficient guarantees that it will avoid similar purchases in the future and has therefore failed to meet the conditions under which the US administration could certify to Congress that the security risks to the F-35 program had been removed.Washington has not closed the door on negotiations, allowing both sides to maintain the appearance of moving forward even though the legal situation has barely changed since Türkiye was expelled from the program. The letter appeared shortly after the NATO summit in Ankara, where Donald Trump, during a meeting with Turkish President Recep Tayyip Erdogan, said that sanctions on Türkiye could be lifted and indicated that the F-35 issue would be resolved positively. He did not announce a signed contract or specify a delivery date, but his words created the impression that the White House had already reached a political decision and that only technical obstacles remained.Erdogan referred to the aircraft previously produced for Türkiye and expressed confidence that Trump would honor his promise. The exchange was aimed as much at the public in Türkiye as at Washington, since Ankara wanted to show that the long-running dispute was approaching a settlement and that the personal relationship between the two presidents could again reshape bilateral ties.The present deadlock, however, reveals the limits of such diplomacy. Trump may see Erdogan as a useful ally and support Türkiye’s return to American weapons procurement, but presidential approval alone is not enough. The restrictions are embedded in US legislation, which prohibits the transfer of F-35s while Türkiye retains the S-400, and they are reinforced by a bipartisan group in Congress whose objections range from the Russian system itself to Erdogan’s domestic policies, Ankara’s ties with Hamas, its disputes with Israel, Greece and Cyprus, and the wider perception of Türkiye as an unpredictable ally. Read more Trump’s flirting with Türkiye is making Israel squirm From F-35 partner to pariahTürkiye was never merely a customer. Ankara joined the F-35 project at an early stage, invested in its development, planned to acquire around one hundred aircraft, trained pilots and technical personnel, and integrated domestic companies into the international production chain.Hundreds of components were manufactured in Türkiye, including parts of the center fuselage, landing gear, air intakes, wiring systems, weapons-bay structures, and selected engine components. For Ankara, participation meant more than acquiring a modern fighter. It offered long-term industrial orders, manufacturing experience, access to advanced aviation practices, and a stronger position within NATO. After Türkiye’s exclusion, the Pentagon had to move production to alternative suppliers, while Ankara lost both the aircraft and a network of industrial cooperation around which companies, specialists, and public investment had already been organized.The rupture followed Türkiye’s purchase of the S-400, whose first components arrived in 2019. Ankara argued that Washington had failed to offer acceptable terms for the Patriot system, had not provided the desired technology transfer, and had ignored Türkiye’s urgent need for long-range air defense. For Erdogan, the Russian contract also carried political value because it demonstrated that Ankara could choose its own weapons without submitting to Western pressure. After the attempted coup of 2016 and the deterioration of relations with the US, the S-400 became part of a wider effort to show that Türkiye could pursue an independent policy while working with both Russia and the West.Washington saw it differently. The S-400 was designed to detect and engage advanced aircraft, and its radars could theoretically gather information about the F-35’s stealth characteristics, electronic signatures, and operational patterns. Even without integration into NATO networks, the physical presence of the Russian system alongside the F-35 was considered an unacceptable risk. Ankara’s proposals for a technical commission or separate operation of the two systems did not change the US position. Türkiye was removed from the program, pilot training was halted, aircraft already produced for Ankara were withheld, and sanctions were imposed on its defense industry.The S-400 has therefore changed from a symbol of strategic autonomy into a political burden. Ankara cannot fully activate it without risking another crisis with NATO, but returning it to Russia, transferring it to a third country, or dismantling it would amount to an implicit admission that the original decision was a mistake. Read more How Türkiye went from problem child to power broker in NATO The Israeli factor and resistance in CongressIsrael’s opposition has become an additional and possibly more difficult obstacle, particularly as relations between Türkiye and Israel have moved from periodic crises to lasting strategic distrust.Israeli Prime Minister Benjamin Netanyahu has openly opposed the transfer of F-35s to Türkiye, arguing that it would disturb the regional balance of power. He has accused Ankara of aggressive ambitions, linked the issue to Erdogan’s anti-Israel rhetoric and Türkiye’s political relationship with Hamas, and portrayed the potential sale as a decision that would strengthen a state increasingly willing to challenge Israel.These concerns go beyond the personal hostility between Erdogan and Netanyahu. Türkiye has large armed forces, a developed drone industry, an increasingly capable navy, a growing missile sector, and a military presence extending from Syria and Iraq to Libya and Somalia. Access to the F-35 would provide Ankara not only with a modern strike aircraft but also with experience in fifth-generation operations, advanced data-sharing systems, intelligence capabilities, training, and maintenance technologies that could later support Türkiye’s own KAAN fighter and other national programs.From Israel’s perspective, Türkiye’s possession of the F-35 could eventually restrict the freedom of action of the Israeli Air Force in the Eastern Mediterranean and the wider Middle East. The preservation of Israel’s qualitative military edge has been a central principle of US regional policy for decades, and although Israel operates its own modified version of the F-35, the emergence of a comparable Turkish capability would narrow the existing gap and lead Israel to demand compensation, additional weapons, and technological restrictions on any aircraft delivered to Ankara.The influence of the pro-Israel lobby should not be reduced to the image of a single secret organization directing US policy. It functions instead as a durable network connecting Israeli diplomacy, members of Congress, think tanks, civic organizations, political donors, and parts of the defense establishment, all of which treat Israel’s military superiority as a long-term American interest. Its strength lies in converting Israeli concerns into bipartisan letters, committee hearings, budget amendments, and legal restrictions that remain effective regardless of the president’s personal position.In Türkiye’s case, this resistance is reinforced by Greek, Cypriot, and Armenian organizations and by legislators who oppose Ankara over its domestic politics, ties with Russia, and support for Hamas. The coalition against Türkiye’s return is broader than the pro-Israel lobby alone, but the Israeli factor gives it its strongest strategic justification.For opponents of the sale, the question is not only whether Türkiye has formally met the S-400 conditions, but whether strengthening Ankara serves the long-term interests of the US and its principal Middle Eastern ally. Trump’s insistence that no one will dictate which weapons he can sell may reflect irritation with Israeli pressure, but it does not eliminate the institutional influence behind that pressure. Read more Türkiye is headed for a perfect storm Türkiye between the S-400, its own defense industry, and Western techThe years of sanctions have strengthened a conclusion already widespread within Türkiye’s political and military establishment. The country cannot consider itself a fully independent power while the production of critical weapons depends on decisions taken in Washington, Berlin, Ottawa, or other foreign capitals.This explains Ankara’s investment in the Bayraktar and Anka drones, the KAAN fighter, the Hurjet trainer and light combat aircraft, the Kizilelma unmanned combat aircraft, MILGEM warships, Roketsan missiles, the SIPER air defense system, and the emerging Steel Dome architecture. Türkiye’s defense industry has become an instrument of security, foreign policy, exports, and regional influence.Yet these achievements do not amount to full technological independence. Early versions of the KAAN depend on American F110 engines, and Türkiye still imports engines, gas turbines, optical equipment, microelectronics, machine tools, specialized materials, and electronic components for aircraft, drones, warships and air defense systems. Ankara can design and assemble complex platforms and integrate domestic missiles, radars, and communications systems, but it does not control the entire production chain, especially in aircraft engines, semiconductors, and advanced materials.This is why the F-35 remains important despite the development of the KAAN. The national fighter is a long-term project, while the Turkish Air Force must address the ageing of its current fleet, preserve NATO interoperability, and prevent the technological gap with Israel and Greece from widening. A return to the program could also restore part of the lost industrial cooperation and provide operational experience that declarations of strategic independence cannot replace.Türkiye will therefore probably seek a compromise with Moscow over the S-400, possibly through deactivation, transfer to a third country, return to Russia, or another arrangement that would allow Washington to certify that no operational system remains on Turkish territory. At the same time, Ankara is unwilling to damage relations with Moscow openly because Russia remains important in energy, trade, tourism, Syria, the South Caucasus, and the Black Sea. Erdogan does not want to choose between Moscow and Washington because Türkiye’s foreign policy has been built around cooperation with rival centers of power and the benefits created by their competition.The F-35 dispute nevertheless shows that this strategy has limits. Türkiye’s need for advanced technology, the requirements of its air force, and its NATO membership push it towards the American aircraft, while retaining the S-400 supports its claim to strategic autonomy and its special relationship with Russia. Reconciling the two is becoming increasingly difficult.Even if Trump ultimately approves the sale, Congress is unlikely to readmit Türkiye without substantial conditions. What is often called the American deep state is, in this case, not a hidden command center but a combination of legislation, congressional committees, military bureaucracy, intelligence assessments, lobbying networks, and deeply rooted alliance commitments. When this system must choose between accommodating Türkiye and preserving Israel’s strategic advantage, it generally favors the latter.For Ankara, the dispute is another test of its foreign-policy model. Türkiye can continue diversifying its relationships, developing its defense industry, and seeking compromises with Moscow and Washington, or it may have to accept that access to the West’s most sensitive technologies requires abandoning some earlier choices. Given domestic economic pressure, the enormous cost of national defense programs, rising regional tensions, and Erdogan’s determination to maintain the image of an independent leader, the decision is genuinely difficult. Concessions over the S-400 would look like retreat, abandoning the F-35 would preserve Western restrictions for years, and attempting to keep both the Russian system and access to the American aircraft would most likely leave Türkiye in the same deadlock it has faced since 2019.