Probably nothing, if I lived in America and it was the same as NK is right now there wouldn't be anything I could do. Everyone would be brainwashed and they wouldn't know any better. Even if they don't like the situation or if they don't agree with it there's nothing they can do cause the majority will be against you, while fearing for their own life. My best bet would be trying to escape, even though I'd probably get caught, still better than living there though. People wouldn't start an assassination group, IMO it's delusional to think it's possible that a few people can make a difference in such a brainwashed and controlled country.