The diplomatic aspects of the game can get quite convoluted and complex and it seemed unlikely that Hasbro could accommodate everything that might arise in a game with human opponents. Over the past few months, those fears have been put to rest. While it's not perfect, the diplomatic interface is remarkable. The design team has boiled down all the intricate and mixed messages that are passed back and forth in the board game and reproduced them in an interface that is clean and easy to use. While it doesn't offer the long-term negotiations that are often so integral to many players' strategies, it does permit some pretty flexible planning and negotiation turn to turn.
Some powers respond more to the honeyed voice of the diplomat.
Others respond better to threats and intimidation. The diplomacy phase begins in an assembly room. From here you can go study the map or withdraw with other players to secret meeting rooms. You may ask the other player to attack or ally with any other player. Or ask them not to attack or ally with the selected player.