The MiG-21F-13 was feared by the west at the time, as it was the first truly capable supersonic Soviet interceptor armed with both cannons and heat-seeking missiles. My father, who was in the Royal Australian Air Force during the 1960's used to talk about how Indonesian 21s would regularly perform border incursions to either intimidate or to draw Australia into conflict. A lot of western nations were worried though at the rate at which the F-13 started appearing in the air forces of smaller, Soviet-aligned nations. At the time, with exception to the USA, most nations were fielding outdated 1950's designs such as the F-86E/F, Hunter, or even Gloster Meteors. So it was no surprise that this variant was feared!!
Come 1965 though, the tides turned and the MiG-21F-13 (which was still the primary fighter for many smaller Soviet-aligned states) was outdated as supersonic aircraft such as the Mirage III, English Electric Lighning, F-100 etc started to appear in many air forces.
Anyway look forward to the Mirage III series