Ace combat X:Skies Of Defection

Synopsis
The Federal Republic of Aurelia is a peaceful and wealthy nation located on the southern edge of the South Osean continent. Its mild climate and vast underground resources have kept Aurelia out of war and conflicts for many decades. Contrary to Aurelia's prosperity, its northeastern neighbor, the Democratic Republic of Leasath, was embroiled in a long civil war for many years, until the war came to an end one year before the events of the game.

Under the command of General Diego Gaspar Navarro, Leasath invades Aurelia, claiming the war as retaliation for Aurelia's supposed involvement in the Leasath Civil War. Aurelia, unprepared for the invasion, is almost entirely taken over in under ten days due to the power of Leasath's advanced superweapon, the cloaked airborne fortress Gleipnir.

Reduced to a single operating air base, Aubrey Air Force Base, the remnants of the Aurelian military band together to strike back at the invading Leasath forces. At the forefront of this crusade is the last of the Aurelian Air Force, led by ace pilot Gryphus 1, who—as one of the last survivors of the Gryphus Squadron after an attack by the Gleipnir—bears the mark of the Southern Cross. As Aurelia's last hope, Gryphus 1 must liberate his country from the Leasath occupation forces.

The cutscenes follow Albert Genette, an investigative journalist and a returning character from Ace Combat 5: The Unsung War. While writing a story about the war, he uncovers concerning evidence that points to the war being a front for a Leasath conspiracy to develop an ultimate weapon.