Saboteur Achievement in Mass Effect 3
Disable a group of fighter squadrons.
How to unlock Saboteur
This is a side-quest unlocked after completing the main story mission "Priority: Geth Dreadnought." It will be marked as "Geth Comm Hub" on the galaxy Map. The main quest will appear near this one (labeled "Reaper Base") if you do "Rannoch: Admiral Koris" first - make sure you DO NOT do that mission before completing this, or this one will not be available anymore.
Obtained: After completing the mission Rannoch: Geth Fighter Squadrons.