The Free Erusea uprising (自由エルジア蜂起) was a terrorist insurgency in late 2006 on the Usean continent. Free Erusea—an organized network of former Federal Erusea Air Force officers—captured an old munitions factory in White Valley and attacked various locations throughout the continent. The Independent State Allied Forces formulated Operation Katina in response, sending Mobius 1 and AWACS SkyEye to quell the rebellion.
One year after the conclusion of the Continental War, Erusea's interim government continued efforts to reform under the guidance of ISAF observers. However, the provisional government received a great deal of criticism from within Erusea; elements of the Erusian military did not approve of the new reforms and rebelled against the ISAF occupation forces. The rebels, calling their movement "Free Erusea", were led by a number of high-ranking Federal Erusea Air Force officers and captured an old munitions factory in the White Valley Bay region. Using its newly acquired cache of weapons, the Free Erusea forces attacked the ISAF in Erusea and across Usea.
After reviewing tactical data from the Continental War, ISAF command had reached the astonishing conclusion that the combat capabilities of ace pilot Mobius 1 were equal to that of an entire ISAF fighter squadron. Consequently, ISAF command entrusted the suppression of the Free Erusea movement to Mobius 1, who would be supported by AWACS SkyEye once again.
The operation's widespread nature took the small strike force across the entire continent. Combat had broken out again in areas such as Mount Shezna and Newfield Island. The Free Erusea forces, which consisted mainly of helicopters, fighters and transport aircraft, relied on air strikes to compensate for its lack of ground forces. Despite Mobius 1's strategic interception of the rebels' transports, Free Erusea was still able to mobilize its sizable fighter aircraft assets.
Large aircraft carriers, destroyers and bombers were also intercepted and dispatched by Mobius 1. As Free Erusea's losses mounted, the rebel forces mobilized en masse near their headquarters along the White Valley coastline. The rebels had established their headquarters in the captured munitions factory, which also supported an airstrip and naval shipyards, as well as petroleum extraction and refinement facilities. Mobius 1 confronted the Free Erusea forces head-on and inflicted massive damage to the rebels' crippled armada. Multiple rebel fighters and transports were shot down as well, and it soon became apparent that Mobius 1 and the ISAF would emerge victorious.
Just as the last of the Free Erusea forces were eliminated, Mobius 1 was engaged by a squadron of experimental X-02 Wyverns, which had entered the airspace undetected. The Erusian X-02 was the pinnacle of unmanned aviation technology and supported advanced avionics and flight control systems. Mobius 1 became entangled with the Wyverns and an intense dogfight broke out over the munitions factory. Despite the Erusians' numerical and technological advantage, Mobius 1 defeated the X-02s and safely returned to base.
The Erusian threat was neutralized. ISAF ground units would soon after swarm the base and capture the rebel leadership. Additionally, data on Erusea's secretive X-02 fighter program were recovered by the Allies and used to further advance the ISAF Air Force's own technological strength. Once the Free Erusea rebellion had been subdued, the interim Erusian government's reforms and reconstruction efforts resumed and proceeded smoothly; hostilities had once again ceased on the Usean continent.
- During the mid-air refueling mission, an Osean flag can be seen on the tail of the KC-10 tanker since the model also appears during the main campaign for Ace Combat 5: The Unsung War, where the player flies for Osea.
- "Katina" is also the name of a planet from Nintendo's Star Fox series. The operation's name may be referring in particular to Star Fox: Assault—both Nintendo and Namco were part of the game's development team.