Turkey’s F-35 Return Is Still Blocked by the S-400

Why Turkey was removed from the F-35 program

The dispute began with Turkey’s acquisition of Russia’s S-400 air-defense system in 2019. Washington argued that operating the Russian system alongside the F-35 would create security and interoperability risks, particularly for the protection of sensitive information about the aircraft. The purchase led to Turkey’s removal from the F-35 program and to U.S. sanctions under the Countering America’s Adversaries Through Sanctions Act, or CAATSA.

Turkey had been involved in the F-35 program as a partner and had planned to purchase at least 100 aircraft. It reportedly invested about $1.4 billion in the program before being excluded.

The legal obstacle Trump cannot remove alone

Section 1245 of the FY2020 National Defense Authorization Act prohibits the transfer of F-35 aircraft to Turkey. The executive branch can waive that prohibition only after certifying that Turkey no longer possesses the S-400 or associated equipment, has given credible assurances that it will not reacquire the system, and has not made another Russian defense purchase that would increase the risk to the F-35. The waiver can take effect only after a 90-day period.

That means a presidential announcement is not enough to complete the sale. A State Department letter to Congress in July said Turkey had not yet met the legal conditions required to receive F-35 aircraft.

Congress is also a significant constraint. Lawmakers have expressed strong concern about any sale, and the statutory language means that the administration cannot simply treat sanctions relief as equivalent to Turkey’s return to the program.

What remains unclear about the S-400s

The decisive question is whether Turkey has genuinely stopped possessing the S-400 system—not merely whether the missiles are inactive or stored. U.S. law refers to possession and associated equipment, while the legal framework also requires assurances against reacquisition.

Public reporting has discussed the possibility of Turkey transferring or otherwise disposing of the systems, but the supplied sources do not establish a final, publicly confirmed arrangement that satisfies the law. A report in August described the F-35 purchase as stalled while the S-400 requirement remained unresolved.

Until Ankara’s status is resolved and the required U.S. certifications are made, Trump’s promise remains an opening for negotiations rather than an executable F-35 transfer.

Erdoğan’s broader regional agenda

The F-35 dispute is unfolding alongside Erdoğan’s effort to promote Turkey as both a NATO ally and an independent regional security power. In August, Turkey, Saudi Arabia and Pakistan signed the Mecca Joint Defense Agreement. The pact says an armed attack on one signatory would be treated as an attack on all three, creating a collective-defense framework among the three countries.

Turkish officials have described the agreement as defensive and not directed at Iran or another specific country. Erdoğan has said the framework is open to additional regional participants and that its vision is not limited to the original three signatories. Egypt has been discussed in reporting as a possible target of diplomatic outreach, but it is not identified in the supplied sources as a confirmed member.

The available reporting supports Erdoğan’s broader emphasis on regional security cooperation and greater regional ownership. It does not establish specific new commitments concerning a visit to Syria, support arrangements for Syria or a defined Gaza-reconstruction package. Those claims should therefore be treated separately from the documented F-35 and Mecca-pact developments.

The bottom line

Erdoğan says Trump promised Turkey a path back to the F-35 program. Trump did pledge sanctions relief and signaled that a sale could be considered. But Turkey has not yet cleared the most important hurdle: U.S. law still requires it to no longer possess the S-400, and the State Department has said the legal conditions have not been met.

The result is a gap between political messaging and legal reality. Turkey’s return would require a verifiable resolution of the S-400 issue, executive certifications and a sale able to withstand congressional scrutiny—not simply a promise made at a NATO summit.