Deimos was destroyed during the Earth-Mars conflict, following the Battle of Ganymede. The UN took this action in response to Mars' nuclear annihilation of the Earth-Mars joint Phoebe Research station along with the consequent destruction of the moon itself. Earth's government declared the Phoebe demolition a provocation, despite Earth itself previously sending its own ship to trail Martian ships at a number of stations. In the case of Phoebe, Earth actually had the UNN Nathan Hale attempt to reach Phoebe before the MCRN Scirocco. This occurs soon after Rocinante and Guy Molinari take Thoth station in the TV show.