Negotiating with the crazies... (CYOAH! Redux)

The Promethean Empire. A fanatical, idiotic nation, bent on dominance of the Galaxy. A pipe dream, then. They could be a useful resource though. You have free rein. A Promethean Delegate let slip that they are planning on invading Earth. What will you do?
 * Pledge the full support of the Praetorian Empire
 * Let them take Earth. It isn't our problem
 * Go to war on Earth's behalf
 * Gain allies before you act