In addition, a Pearl Harbor style attack by Yuktobanian forces on Port St. In many ways Osea is meant to resemble the United States thematically, while Yuktobania is a loose caricature of Russia. A conspiracy by a Belkan paramilitary organization posing as both Yuktobanian and Osean fighter squadrons leads to war. In the 15 years after the dramatic end of The Belkan War, relations between the nations of Yuktobania and Osea sour in a similar fashion to US-Soviet relations after World War 2. During the Belkan War Yuktobania and Osea were unified and fought to combat Belkan aggression, as the United States and Russia cooperated to fight Nazi Germany.

The fictional Belkan War (explored further in Ace Combat Zero: The Belkan War) is the foundation on which Ace Combat 5's Circum-Pacific War is built upon, and resembles in many respects the German invasion of greater Europe in 1939 along with their eventual defeat. The geopolitical aspects of Ace Combat 5's universe in particular run parallel to to World War Two and the ensuing Cold War. The ISAF dispatches Mobius One and AWACS Sky Eye to quell the extremists. One year after the conclusion of the Usean Continental War in Ace Combat 4, Erusean extremists have captured a weapons factory and resumed attacks on the ISAF. In Arcade Mode, the player resumes control of Mobius One. The members of Wardog Squadron go from heroes, to demons, to ghosts in an ambitious story chronicling the war throughout its duration, and the conspiracy that started it. Jack Bartlett and Kei Nagase are the sole survivors of a brutal attack by what turn out to be Yuktobanian aircraft on a flight training exercise at Sand Island, one of a number of incidents that lead Osea into all out war with Yuktobania. Davenport (Chopper), Kei Nagase (Edge) and flight lead Jack Bartlett (Heartbreak 1). The squadron initially consists of Alvin H. The player takes on the role of Blaze, a trainee pilot in the Osean Air Defence Force who is called into active service with Wardog Squadron, based out of Sand Island Air Base. The game received critical and commercial success following its release. In Europe the game was released as Ace Combat 5: Squadron Leader. Released on Octoexclusively for the PlayStation 2, Ace Combat 5: The Unsung War is the fifth game in Namco Bandai's flight combat series and the second game on the PlayStation 2, preceded by Ace Combat 04: Shattered Skies, and followed up with a prequel, Ace Combat Zero: The Belkan War.

Ace combat 5