The MIG 25 as I remember it was designed as an answer to the F15 eagle,which heavily influenced it's design more than anything else.They were both
latter day dog-fighters and the major difference was the use of thermionic valves in the MIG which wouldn't be effected by an EMP (Electro Magnetic
Pulse) in the event of a nuclear bomb detonation,when the transistors used in the Eagle and all other modern aircraft would be fried by it and fall
out of the sky while the Foxbat carried along on its merry way.
(All this from memory from a VERY long time ago,so excuse any inaccuracies please).

