Blue Comet SPT Layzner (1985)

In an alternate 1996, the US and USSR take the Cold War to Mars. A group of teenage cadets, the Cosmic Culture Club, are sent as a message of goodwill to both sides by being assigned to the neutral UN base on Mars. However, it's not long before their visit is interrupted by a group of unidentified giant mecha that battle around the base, leading to the deaths of many personnel and teenagers. After reaching shelter and failing to communicate with the US or USSR bases on Mars, the group is approached by a young man named Eiji, who informs them that he's from a planet called Grados and that the Earth is in danger.