The Overlord wrote:
Sometimes there cannot peace between nations, if a particularly bad regime exists is power in one of these nations. As long as the Nazis controlled Germany, there was never going to be peace between Germany and its neighbours. The same deal with Cardassia, as long as Cardassia was controlled by a military, there would never be peace between cardassia and the Federation, there was only peace after that government was gone.
You cannot compare intraspecies and interspecies issues. I am all for waging war against imperialist forces like the nazis. In the fictional world of Trek on the other hand there are a lot of folks who want the whole galaxy for themselves. Romulans, Klingons, Cardassians, the Dominion, even the Ferengi aspire to control everything and everyone. Yet peace, often a fragile one, with the Federation is possible and preferable from the view of the UFP. The reason should be obvious, there are so many of them! You cannot wage war against a dozens of species who have an agenda of total domination. It would be extremely bloody, extremely costly and sooner or later make you resemble your enemy more and more and the lines written in your constitution less and less. We saw what Federation officers have been willing to do during the Dominion War.
None of this doesn't imply that the peace treaty between the Federation and the Caradassians is perfect. The logic is probably a pretty cruel one, accept a few issues in the DMZ in order to prevent another war with millions of casualties. That's a natural problem of managing large political entity like the Federation and the Maquis had a point, they had to suffer such that other people did not have to.
And the Romulans didn't honor that treaty either, the Federation did not develop cloaking tech and the Romulans did everything besides open war fare to undermine the peace between them and the Federation. I don't see how planning to invade to Vulcan is abiding by a peace agreement. Sometimes I think the Federation has the worst diplomats ever, where their whole strategy is to give the other side everything it wants and hope they won't come back with more insane demands later.
Like I said before a contract where one side doesn't honor it isn't worth the paper its printed on, if you sign a peace treaty and the other side has no intention of honoring it, its worthless.
Also considering civilizations in Star Trek were often supposed to allegories for nation states in the real world, I think we should be comparing these civilizations to real world nation states.