Türkiye wants back into America's F-35 programme, but a $2.5 billion Russian purchase still stands in the way. Ankara reportedly explored transferring its largely unused S-400 air-defence systems to the UAE, potentially removing the biggest obstacle to an F-35 comeback. That escape route has stalled, with no completed transfer officially confirmed. The UAE faces its own dilemma: it operates US Patriot and THAAD systems, hosts American forces and has itself pursued the F-35. Taking Türkiye's Russian S-400s could import the same security and sanctions concerns that damaged Ankara's relationship with Washington. Russia adds another complication: Moscow has confirmed discussions with Türkiye over the system's fate, while contractual restrictions could affect any onward transfer. Meanwhile, the US State Department says Türkiye still has not met the legal conditions for F-35 access. One Russian weapons purchase continues to haunt Erdogan's stealth-fighter ambitions.