I am tempted to make the hatred reciprocal just to see what happens. Never been involved in a war that had that.
I was, a long time ago. But that had been a IC rivalry for so long (Sartania vs Arcachon). But if you declare hatred also, you'll be at hatred forever untill one destroys the other. Is the conflict/culture truly deserving of that? There will be no way of 'better relations' when a new government takes over etc.