The stuff that came after it with Rooster coming to his aid and saving him from those evil Canadians (I’m guessing. Could have been anyone), leading them to steal a F14 to escape was nicely done as well.
It doesn't really matter, and the filmmakers went out of their way to not identify any particular country, but, if you want to take a guess based on what was shown in the movie, I would guess Iran for the following reasons:
- Iran is the last operator of F-14s in the world, having some left over from their per-Revolutionary days when they had good relations with the US. They've been spotted flying escort for Russian cargo planes into Syria as of a few years ago, so they're still active.
- Iran is notably eager to develop nuclear weapons, so the uranium enrichment facility being theirs makes sense.
- Iran is extremely mountainous and snowy in parts.
- The carrier was able to strike from the ocean without the planes needing to refuel, meaning the target was likely in a coastal nation like Iran.
- Iran recently asked Russia if they could purchase some of the Su-57 Felon fifth generation fighters seen in the film. Russia refused, for now, but in a few years, who knows? Alternatively, just as the Iranians flew escort duty for the Russians in Syria, it's entirely possible Russian pilots could be providing security for Iran's uranium enrichment facility. Normally Russia would try and discourage Iran's nuclear program, but if the wake of NATO expansion due to the Ukraine situation, they may reevaluate that stance.
- Iran doesn't typically operate Mi-24 Hind helicopters, but they did capture some of Iraq's during the Iran-Iraq War and after many Iraqi military forces defected to Iran during the US invasion of Iraq in 2003, and have one on display in their military museum, so it's possible they kept a few in flying condition, cannibalizing parts from others.
- In the first movie, the nameless bad guys went after a ship that drifted off course in the Indian Ocean, which borders Iran. Another reason Maverick may have been approved for this mission was his experience facing the same enemy before, if they were in fact the same enemy.