Right, that’s about the time we were all worried about the MiG 25 Foxbat, the greatest plane ever to fly. Turned out to be junk once we got the defector to bring us a copy.
The Foxbat was a good plane for what it was designed for - intercepting bombers. And yes, it had vacuum tubes, at the time a good application for operating in a nuclear environment. It was never intended as an air superiority fighter. It’s successor is the MiG-31 Foxhound, still a pure interceptor.