The Long Road to the Current Moment

Türkiye was once a major participant in the multinational F-35 program and had planned to purchase the advanced U.S.-made fighter. Turkish companies were also part of the aircraft’s supply chain.
The relationship changed after Ankara decided to acquire the Russian S-400 air-defense system in 2017. The first components of the system arrived in Türkiye in 2019. Washington argued that operating the Russian system alongside the F-35 could create security risks, including possible exposure of sensitive information about the aircraft. The United States removed Türkiye from the F-35 program in 2019. In December 2020, the U.S. imposed CAATSA sanctions on Türkiye’s Presidency of Defense Industries, known by its Turkish acronym SSB. The sanctions created additional obstacles to defense transactions and export licenses. The dispute has repeatedly appeared close to resolution, only to stall:

• Ankara has argued that it needs an advanced air-defense capability and that it was not offered acceptable alternatives at the time it acquired the S-400.

• The United States has maintained that Türkiye cannot possess the S-400 and receive F-35 aircraft.

• Turkish officials have sought a formula that protects Türkiye’s defense interests without appearing to surrender national sovereignty.

• Members of Congress have remained skeptical of restoring high-end defense cooperation without a clear, verifiable resolution of the S-400 issue.

The result has been years of negotiations, public signals, and incomplete progress.

The KAAN Engine Sale: A More Immediate Test

The more immediate issue may be the proposed U.S. sale of approximately $700 million in General Electric F110 engines for Türkiye’s indigenous KAAN fighter aircraft program.
The F110 engine is important because the KAAN program is intended to reduce long-term dependence on foreign combat aircraft. Early versions of the KAAN are expected to rely on U.S.-made engines while Türkiye continues developing a domestic engine.
The Trump administration’s move toward the engine sale signals a willingness to re-engage with Türkiye on defense-industrial cooperation. However, it has also triggered congressional criticism. Critics argue that the administration should not bypass or minimize congressional review while CAATSA-related questions remain unresolved.

Best-Case and Worst-Case Scenarios

Best-Case Scenario: The U.S. and Türkiye reach a transparent agreement on the S-400s. The Trump administration formally lifts CAATSA sanctions, Congress allows the F110 engine sale to proceed, and the two allies rebuild defense cooperation. This would keep the KAAN program on track and stabilize the relationship within NATO.

Worst-Case Scenario: Negotiations fail if neither side can agree on the S-400’s status or if Congress blocks the deals. In this outcome, Türkiye could accelerate its search for non-U.S. defense alternatives, and the strategic relationship would remain transactional and fragile.

What This Means for Turkish Americans

For Turkish Americans, this issue is a measure of whether the United States and Türkiye can manage serious disagreements while maintaining a productive alliance. A sustained improvement in relations can create more opportunities for trade, education, and investment. Turkish Americans can encourage a more accurate discussion that recognizes both U.S. security concerns and Türkiye’s security priorities. Staying engaged with elected representatives and supporting fact-based advocacy is essential during this transition period.