They’ll still have to get those planes eventually if they don’t want to be incredibly outgunned by all other NATO members therefore left irrelevant when it comes to the air. However with TF-X already planned to come out in a decade… when next generation of fighter planes comes around the corner they will never trust the US with a program.

Now that UK is out of the EU and well they still want to be not completely dependent on the US as well. UK most likely looking for the same thing as Turkey in this case. UK already has big assets in the Turkish defence industry and well Turks really can’t do the same in the UK so with this move and further investments UK most likely wants to secure Turkey as a secondary partner in a future fighter plane project once TF-X is done.