Only two tricks remain and I must win the trick containing GREEN 5. All other greens are already out (G1-4,6-9 seen), so my GREEN 5 is the last green in the game. If I lead GREEN 5 now, no one can follow suit and they can safely discard; as long as teammates avoid playing rockets, I win the trick immediately and the task is completed this trick. If instead I lead ROCKET 4 now, I win trick 9 but risk causing someone to discard their last non-rocket and end up with only rockets for the final trick, forcing them to trump my GREEN 5 and fail the mission. Therefore, leading GREEN 5 now maximizes success and immediately secures the task if teammates cooperate (which they should).