@Willy VerebI figured as much; since I was going to do it in my next post I just wanted to be sure.
I plan to escalate with the following orders of events:
1) Hundreds of thousands of additional soldiers sent (happening right now)
2) Crackdown on terrorism and native uprisings that is already beginning. Really bad human rights violations which the PRK insurgents or any Yllendthyr spies could easily see, document, and share with the rest of the world.
3) Tin closing that strait and enacting the embargos on the north, likely going to be a direct result of this meeting.
4) Waves of refugees fleeing to the Yllendthyr side, followed by Tin moving a large force to the borders to stop them.
5) Tin denies any accusations of human rights violations and such from other nations, and once again accuses Yllendthyr of terrorism but this time to the entire world. In addition, they claim that their military presence on the borders is because Yllendthyr is so awful that hordes of refugees are fleeing to the Tinite side of the island, and Tin doesn't yet have the resources over there to "save" them.
6) Tin formally severs all foreign ties to Yllendthyr in a spectacular fashion, as we briefly discussed in our PMs.
7) ???
8) Tin begins to occupy some of the smaller uninhabited or barely populated islands that Yllendthyr claims. (These are too small to be on the map; I'm taking the liberty of assuming that there are tons of little keys and atolls with 0-250 people on them)
9) ???
10) If Yllendthyr hasn't attacked yet, Tin will.
I'm open to any suggestions for additional stuff but that's my plan. The question marks are places where Tin's response depends largely on how the world reacts.