User blog comment:Damac1214/Call of Duty: Advanced Warfare Reveal Trailer has Dropped/@comment-1187559-20140502225249/@comment-4921618-20140503022412

To quote a person answering a similar question on reddit.

"Maybe to start the trilogy you are the bad guys, you turn rogue and go against Spacey and everything he stands for after a while."

It seems the most likely course.