Many countries aren’t trusted enough by the US in particular to be allowed F-35 purchasing. Turkey, wayward NATO ally that it is, got booted from the F-35 program because they were also buying Russian air defense systems (S-400 IIRC), and the US didn’t want to hand over a Gen 5 stealth jet to an S-400 operator which would give Russia precise data on its radar signature.
Many countries aren’t trusted enough by the US in particular to be allowed F-35 purchasing. Turkey, wayward NATO ally that it is, got booted from the F-35 program because they were also buying Russian air defense systems (S-400 IIRC), and the US didn’t want to hand over a Gen 5 stealth jet to an S-400 operator which would give Russia precise data on its radar signature.