The Northrop F-5 is a second-generation fighter that were used as MiG-28s in Top Gun.
Trivia
The F-5s used in the movie were actual U.S. Navy F-5s that were used at TOPGUN and repainted for the movie. The Navy utilizes the F-5 as an aggressor aircraft at TOPGUN to simulate enemy aircraft. The F-5 replaced the ex-U.S. Air Force T-38 Talons that the Navy had borrowed for use at TOPGUN for dissimilar aircraft combat training (DACT). As of 2020, VFC-13 at Naval Air Station Fallon continues to use the F-5 at TOPGUN as an aggressor aircraft.