Diplomacy ethics

[militarist]

And the guy who broke the deal, avoided war against him in this way. I was thinking to attack him and questioned our NAP (he did something, I would say, evasive before all this situation), and tell that he should free the province or we should reconsider our NAP (he was made in dependence of some borders agreement, which was ignored by him.). So I proposed to remove his army or fight with me against the closest enemy to this my border. He choose second..and that's result. I'm not complaining just trying to understand the spirit here and what to expect from this "diplomacy".