Escort ships, there are two types of them. Usually a convoy escort with 4 hydra ships or just some fighter beside it. In any case, they can be allied or hostile.
Problem is that with the hostile ships that fire on you as soon as they are in range, if you destroy them, you receive - karma instead of + karma.
Logs: (check for Iridium Haul location, while I was doing the Open Space daily task in the logs - Jericho space)
Video: (this applies to regular Smuggler’s escort (-2 karma issue) and enemy convoy escort (-5 karma issue) instead of + in both cases