US launches a fresh F-35 review for Turkey—can Ankara bridge the S-400 rift?

US Vice President JD Vance said on June 24 that Washington is conducting a review on whether and how the United States could sell Turkey F-35 fighter jets. The key constraint is Ankara’s 2019 acquisition of the Russian S-400 air and missile defense system, which has long been a central obstacle to Turkey’s access to U.S. fifth-generation technology. The statement signals that the issue is not frozen in place, but instead is being actively re-examined by the U.S. administration. While no decision was announced, the framing suggests a potential pathway that would address interoperability, compliance, and security concerns tied to the S-400. Geopolitically, the move tests the durability of NATO cohesion against the backdrop of Turkey’s balancing act between Western security needs and selective procurement from Russia. The U.S. benefits if it can keep Turkey inside the F-35 ecosystem, strengthening deterrence in a region spanning the Black Sea, the Eastern Mediterranean, and the Middle East. Turkey benefits if it can modernize its air force without fully abandoning its prior S-400 investment, potentially improving leverage with both Washington and Moscow. Russia’s position is indirectly challenged because any renewed F-35 pathway would reduce the strategic value of Turkey’s S-400 choice, while also signaling that U.S. technology access can be negotiated. The political risk for Washington is that any perceived concession could trigger backlash from lawmakers and defense stakeholders who view S-400 as a persistent security breach. Market and economic implications are likely concentrated in defense procurement and related industrial supply chains rather than broad macro variables. If the review progresses toward a sale, it would support U.S. aerospace and defense revenue expectations tied to F-35 sustainment, training, and potential upgrades, while also increasing demand for Turkish integration work and subcontracting. The most immediate “market signal” is sentiment in defense equities and contractors exposed to fifth-generation aircraft programs, though the articles do not provide deal size or timing. Currency and commodity effects are not directly indicated, but defense spending expectations can influence risk premia for defense exporters and regional procurement planners. Overall, the direction is mildly positive for U.S.-linked defense industrial sentiment, with uncertainty remaining high until the review yields concrete conditions or milestones. What to watch next is whether Washington specifies compliance requirements tied to the S-400, such as deactivation, removal, or technical safeguards, and whether Turkey offers reciprocal steps. A decisive trigger would be an official U.S. determination that a sale is feasible under defined security constraints, followed by congressional notification and contract-level negotiations. Another key indicator is whether Turkey’s posture toward Russian systems changes in parallel, since U.S. reviewers will likely seek evidence of reduced operational risk. If talks stall, the most likely outcome is a continuation of the status quo, with Turkey remaining outside the F-35 program and U.S.-Turkish defense ties staying transactional. The escalation or de-escalation timeline will hinge on the review’s internal milestones and any subsequent public statements from U.S. defense leadership over the coming weeks.

Geopolitical Implications

• 01

  A potential F-35 pathway would strengthen NATO interoperability and U.S. leverage with Turkey, but could trigger domestic U.S. political backlash over security concessions.

• 02

  Turkey’s ability to modernize while retaining Russian systems would signal a continued Turkish balancing strategy, complicating U.S. standardization efforts.

• 03

  If Washington sets strict S-400 compliance conditions, it could pressure Ankara to renegotiate its Russian defense posture, affecting broader Russia-Turkey defense ties.

Key Signals

• —Any U.S. clarification on S-400-related conditions (deactivation, technical mitigation, or timelines).
• —Turkey’s public or official statements indicating willingness to adjust its S-400 operational status.
• —Congressional or Pentagon notifications that indicate the review has moved from feasibility to implementation.
• —Follow-on reporting on whether interoperability and export-control compliance frameworks are being drafted.