Suggest some sort of in Game Penalty for alliance breakers. Perhaps an algorithm that can figure number of attacks by alliance breakers to weaken the positions of those with whom their supposed to have an alliance. Other than the "break alliance" feature on the card, would be great if an Algorithm can impose a weaker dice roll, inability to use "blitz" mode, or impose a soldier penalty.
As it stands the current alliance is nothing more than a prisoner's dilemma wondering if your alliance maker will break rank or be faithful.
Finally should turn on a communicate feature with those you have an alliance to either better plan alliances or allow you to call your alliance mate out if they're breaking alliance rules.