O país de origem dos MiG 28s (ver nota de rodapé) foi deixado intencionalmente vago. Teria sido fácil ter os pilotos conversando em sua língua nativa ou até adornando a aeronave com esquemas inequívocos de identificação.
That the enemy was never officially established in Proser's early draft or Jack Epps Jr's final script. This was likely intentional: villainous governments in the movies are routinely left vague as to not piss off their real-world counterparts, with the exception of North Korea, possibly because North Korea doesn't have a strong market for movies or video games.
source: Task & Purpose - Brad Howard

Em relação às marcações de identificação:
However, the markings on the fictional MiG-28 aren't Soviet. The MiG-28 in the film has a single red star surrounded by a yellow circle on their tail as their only marking, while Soviet aircraft traditionally had a white trim to their red star (just to cover my bases, the North Korean Air Force uses a blue trim). However, one country does, in fact, use yellow trim on their red star insignia: China.
source: Task & Purpose - Brad Howard

Pelo menos um dos rascunhos do roteiro identificou os agressores como norte-coreanos.
Despite the markings, North Korea is still a good guess. Producers Jerry Bruckheimer and Don Simpson had more than one writer working on the Top Gun script. Along with Proser's draft, Jim Cash and Jack Epps, Jr. were hired to write another draft of the screenplay for the film that initially identified North Korea as the threat that Maverick and Co take on in the thrilling finale.
source: Task & Purpose - Brad Howard
Durante a reescrita do roteiro, o conflito foi transferido para o Oceano Índico, o que confunde ainda mais o problema. Qual nação esportiva dos MiG28 supostamente armados com mísseis anti-navio AM 39 Exocet fabricados na França seria tão protetora nessa área?
Portanto, não há país de origem definitivo.
Aparentemente, os aviões agressores fictícios MiG-28 usados no filme Top Gun eram, na verdade, uma mistura de aeronaves Northrop F-5E Tiger II de assento único e F-5F Tiger II de dois lugares.