game 7974045, can i attack yellow next go? read game chat

Yellow proposed a 3 way truce which i agreed to as i was the weakest. Yellow and Pink attacked each other before anything was agreed. I suggested a 1 turn warning, which yellow agreed to. I've just given yellow a one turn notice before taking my turn. Yellow is saying i can't attack next turn. Just want to know what others think? Would i be breaking the rules if i attack him on my next turn? And if i don't, should't he have to wait till the turn after? Or is he correct, i can't but he can? It might all be irrelevant depending on what red or green do. Just wanted to make sure i'm not breaking the rules and risking getting banned or a warning before taking my next turn. Thanks in advance for any feedback.