Gundam: G no Reconguista Movie III - Uchuu kara no Isan

Synopsis

At Sankt Porto, the spaceships of the Amerian Army suddenly come under attack. The space colony nation of Towasanga has begun its "Reconguista" operation, whose goal is a return to Earth. As four powers from Earth and space gather at Sankt Porto, asserting their respective claims and fighting for their causes, Aida decides to head for Towasanga with Bellri and her comrades in order to seek the truth. In Towasanga, on the far side of the Moon, shocking facts will be revealed to Bellri and Aida... (Source: AllTheAnime)