Ace Combat Infinity is set in an alternate timeline, in which Earth was ravaged by the "Ulysses Disaster". In 1994, a fictional asteroid collides with one of Jupiter's moons, 5254 Ulysses. This event sends about 10,000 meteors heading for Earth, all expected to impact the planet in five years' time. Faced with the prospect of extinction, the world's major superpowers build "Stonehenge", a network of anti-meteor railguns across the planet. The meteor storm finally hits Earth in July 1999. While Stonehenge destroys enough of the inbound meteors to prevent human extinction, the remaining meteors still ravaged about 20% of the Earth's surface, destabilizing the economy and collapsing the world order. The disaster hits Europe and Asia especially hard, forcing the nations to reorganize and create autonomous refugee zones. Twenty years later, the United Nations find itself fighting against terrorist organizations around the world. To better combat the terrorist threat, the UN hires Arrows Air Defense and Security, a private military company specializing in aerial warfare.