How are they oppressing you? Sure they are killing neutral like me, but how are they ruling Tir?
How are they a threat to you? Are they attacking you at all? Or are they just a threat to your cause?
btw, I never said you attacked them because they dont agree with your policies, but rather because you dont agree with theirs. There is a difference, they arent killing you even though they dont agree with you. Maybe they should.