The way the article made it sound, I think they viewed it as their duty. Not that they were told to do it, because the article made it quite clear the this wasn't done with instructions from higher ups --if you believe the higher ups, but that really isn't the point--. I really think that they viewed this as their job and that they had to do it to secure the country. Not that that doesn't make them kind of... messed up in the head.