Ceres

Humanity's oldest colony in The Belt. The decade following The Ground War has seen it largely taken over by Apsis. What was once the farthest into the frontier humanity had ever reached is now the core logistical and manufacturing hub that keeps the calories flowing and the solar system fed.

A direct assault on Ceres is not in the Rebels playbook at this time. Ceres is both:

1. The most densely defended body in the solar system
2. The central nervous system for the entire system's resource distribution network.

Unless and until there is a plan to account for any root-level interruption of the latter that justifies the all-but-guaranteed horrendous losses that stem from the former, command has deemed a strike at Ceres absolutely not worth it.