Quote Originally Posted by Roark
Sometimes an AI faction will bolster a province slightly with no intention of invading, but the player will go "Aha!!", starts an arms race, and war becomes a self-fulfilling prophecy.

Very true. I did this a lot when I started playing - even if they never attacked me eventually I would feel I needed to attack them because I was broke from building troops.

As an aside, I've found it's a good tactic to build an army one province behind my borders and kill any emmisaries that head that way. That way I can have a ready made army to spring a suprise attack or counter-attack with, and I don't prompt my neighbor to start building armies that could stop me because he never sees mine grow.