This makes no sense. The door was closed right? We have a poster in our crew room with a CRJ on it that says "this aircraft could be a terrorists next target...don't make it an easy one." It explains how important it is to close all the doors on the aircraft before leaving it unsupervised. I guess terrorists can't figure out what the "push" and picture of an arrow mean on the outside of the door. We even got a crew memo that said if we approach an aircraft that has any doors open including any cargo doors without a ramper or gate agent watching the aircraft we should contact a ground security agent and fill out a report. So I guess my company needs to figure out who's right on this issue.