In the Army they very much operate on a “Need to Know” basis which means exactly what it says. They have certain departments and ranks within the army and often information is filtered down to only those that need it meaning the foot soldiers may not have the full background behind an operation but know as much as they need to to carry out a task.
Some people question this saying that everyone should have the right to know why they have been asked to do something but in certain situations that is either not possible due to time restrictions or simply not safe. Information get get in to the wrong hands causing risk to everyone involved and the less people that know about security operations the less chance of it getting out.
If you sign up for the army this is one thing that you will need to bear in mind as often you may never know exactly why you had to do something or find out months down the line.