The United States has blocked shipment of F-35 technology to Turkey over a Turkish decision to purchase S-400 surface-to-air missile systems from Russia. Why didn't Turkey wait until they had acquired the F-35 technology and it was fully integrated into their military before going to Russia for air defense technology? The United States would then be unable to prevent Turkey from obtaining both technologies.
Could it be simply an internal acquisition schedule unrelated to politics? Or maybe the sale of F-35s entails long term support that the US could withhold, placing them in the same position they are in today?