In 2030, the "shield" satellite system set up by the major powers in space ends the era of ballistic missiles. The danger of nuclear war is no more. In 2035, the United States fell into a great crisis of ethnic and political conflict. An armed conflict takes place within the United States and make lose its global leadership role. In 2040, the world is dominated by 12 multinational military organizations. The conflicts are getting more intense and the world is facing a new world war. The Endwar.
The RIO (the Rio Pact or the Treaty of Reciprocal Assistance) is a military alliance of South American nations. Established in 1948 in Rio De Janeiro. After the US exited this alliance in 2035, it became the joint military force of the countries of South America. The central principle contained in its articles is that an attack against one is to be considered an attack against them all; this was known as the "hemispheric defense" doctrine.