Well put, General_W. I now understand why you have come across as a war monger: It is actually YOU who is receiving back-room campaign donations from the ironworkers in Meleagerville!
I also now understand that I have been missing the entire point of this discussion. By assuming that Foreign will do their utmost to curb KISS expansion, Defense must responsibly come up with alternative scenarios. That way, if things don't go well with diplomacy MIA still has options.
With this new perspective on the issue, it does change my stance a bit.
Foreign must be able to have a verifiable force to back up its threats. If the diplomat tells KISS: "We must have control over the spices. This actually is a pretty big deal for us, and we're not joking around." we need to be able to back that threat up. I would still only do what is necessary to control the spices, whether that means razing their city, occupying it, or sending four or five warriors to the spicecity as a sort of visible encouragement.
Likewise, if we sense that they will control 3/4 of our continent, we should try and focus our efforts on romoving their access to strategic or luxury resources. If they don't have dyes, or spices, or incense, maybe they will be more likely to sue for peace. Of course, they may just become more determined to win them back. That's where our Hoplites will help gain us an advantage.