This is an example of a project that's part of a larger program, which means you will need to work with other project managers. By asking this question, the interviewer is testing your ability to see how well you work with other teams, while effectively managing your own team. Understanding what you can and cannot control will spell the difference between failure and success. A successful answer will address your previous experience communicating with other team members and the know-how and experience to get a project back on track.