[Hollywood]

They explain it at the end, just watch the end over and over again until you understand. They weren't dead, they were part of a secret military operation (unofficial or official, who knows), to investigate the drug trafficking in the training camp. They wanted to know how deep the corruption went, so Sam Jackson brought in some help, including John Travolta, to figure it out. Its been a while since I saw the movie, so don't mind the generalization. Really it was just a big mess, because they wanted to throw you off so many times that by the time the ending comes, you don't believe it. I enjoyed it, but it still went over the top.