Late Era - Started

[Catquiet]

Kojusoki said:
What is even more, spyes can make unrest so high, that the province will revolt and become independent - and then, as an Independent one, can be rided (you know, peacekeeping forces

I would consider causing unrest in someone else's province with a spy to be an attack in violation of a NAP. If you allow that, you are opening up a huge can of worms.