This scene is truly unbelievable. What an insight into this type of man. Who not only knows what to say and what not to say (while learning all along who the real threat is) but notice how beautifully he makes the case for Michael s return home. As a concerned father he is basically asking them not to try anything but does this without really “asking” obviously. Finally, notice how he throws a very subtle hint at barzini at 5:25 when he says, and Im going to blame some of the people in this room. He so clearly turns towards barzini when he says that letting him know that he knows he was behind santinos assassination. the writing but most of all the acting are ABSOLUTELY LEGENDARY.
The peace agreement with was immediately broken by the failed attempt on Michael's life in Sicily that took the life of his wife Apollonia. The Corleone family therefore was free to take its vengeance against some of the people in the room according to Vito's stated conditions.