Every star system has some level of Civilian and UTA presence.
Many conflicts erupt within a system and it's up to you to interact with them or not.
Choosing to interact with an event or not can have long lasting effects on the system and its inhabitants.
Be aware that the galaxy may entice you to make some hard decisions, like killing friendly ships to gain quick resources, data and especially blueprints.
Mouse over the event markers in the system map to find out exactly what is going on there.
Usually UTA ships are the most likely to cause you trouble when in any given star system.
Their ships blockade all the warp gate exits.
If you want to travel to any new star systems, you'll have to deal with a UTA blockade.