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).

Originally posted by Imagewerx
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).

The other way around Im afraid, the F-15 was developed as a response to the Mig-25

At the time, it was thought that the Mig-25 was a lot more advanced than it was - when one fell into US hands, it was discovered that the Mig-25 had a large contingent of steel in its airframe, making it a lot heavier and thus lower performance.