Well, if I do:
Add Clause -> Pacts -> Cease fire; Peace; Alliance <- These 3 are the only options I get (no war)
And if I choose "Cease fire", then it says: This deal was not very good for us, Olav Haraldsson! (Doesn't make any sense)
We made peace several hundreds years before, now, I want to finish him off, like the others.
Could you tell me step by step HOW TO DECLARE WAR to an AI I'm at peace with? THANKS!
-Go to the nations tab, select Diplomacy->Cancel Treaty. Alliance will cancel to armistace, peace to cease fire, and cease fire to war. Note, that you cannot declare war if you are under Republic or Democracy (unless they do first).