I came up with this idea while reading Honor Harrington series, where diplomacy and intelligence pay a big role in civilizations struggle and from the neat feature from Conquest: Frontier Wars. This suggestion probably for DLC's. Also I hope, that we will have Cold War, as mentioned in last dev stream.

It would help in middle and late sections of the game, when You are in crisis and it would help, if two largest nations, Your future opponents would declare war on each other, to soften them up.

The idea is to force them into war, by tricking them, that lets say the nation "A" attacked the nation "B". How? Stealing the ship or changing its transponder to appear as "A", then You could attack "B" with it. But I don't want to go into details yet and write the wall of text., I know there would be lots of questions and issues with it.

Another thing that I hope is going to happen in DLC with sabotage etc. are assasinations. You could hire assasin that would be hard to trace back to Your nation, or make him appear as someone send by another fraction to kill someone in another faction or blow up ship or station from inside to start war between nations.
I think that it would give even bigger immersion and more ways to deal with civilization issues, when the diplomacy fail.