[lentulusgracchus]

Fiddler was in fact designed as a bomber destroyer. They were deployed aloft as a combat air patrol during the Cold War. I rather imagine, given their operational tempo back then, that the airframes are now extremely tired. See the posts upthread about the shape the Indian MiG-21 Fishbed J/U (and later) fleet is in. The Germans inherited an Eastern Bloc inventory in 1990 and junked the huge majority of the airframes, though I think compatibility was the issue there.

[RayChuang88]

This is why I was a bit puzzled that the Soviets decided on the successor to the Tu-28 was the MiG-31 Foxhound, which didn't exactly sport the big internal fuel capacity of the Tu-28. The Soviets could have produced new build Tu-28's with better engines, a much more powerful radar and the ability to carry 8 AA-9 Amos missiles; it would have been perfect to intercept US bombers coming over the polar regions.