Invasion

Official rule text

49.2 STEP 2—COMMIT GROUND FORCES: If the active player has ground forces in the space area of the active system, that player may commit any number of those ground forces to land on any of the planets in that system. a To commit a ground force to a planet, the active player places that ground force unit on that planet. b The planet may contain another player’s ground forces. c If the active player does not wish to commit ground forces, that player proceeds to the “Production” step of the tactical action.