This is basically a "basic non-aggression pact".
A few observations from the clan rumbles lead to my desire to have swift agreement with new encounters.
1. Winning is often decided by who can expand the fastest.
2. Uncertainty about new encounters' stance leads to precious armies wasted on stacking the commander to prevent elimination and guarding bonuses, rather than capturing neutrals and expanding.
3. A user's reputation is hard to tell without a system. I dont have a way to tell if a user often betrays their promises if I never played a game with them. So without such a system, betrayal is virtually unpunished. So the strategy of betrayal is encouraged by its rewards outweighing its consequences.
To promote cooperative strategies, there needs to be a system to "remember" past betrayals.
https://youtu.be/mScpHTIi-kM