Please expand information about Ace Combat 6: Fires of Liberation.

From Ace Combat Wiki

Belka is a country in the Ace Combat series of games, featured in Ace Combat Zero: The Belkan War. More detail about the war can be found there. In Ace Combat 5: The Unsung War, it is revealed that they were the real culprits in the war, to avenge their defeat 15 years ago.