Dry run (terrorism)
A dry run or a test run is an act committed by a terrorist organization without carrying out any actual terrorism in an attempt to determine whether a technique they are planning to use will be successful. The dry run is part of the rehearsal for a terrorist act, and is often the immediate precursor to the attack. It may include attempting to smuggle weapons or other items to be used in the attack past a security checkpoint to determine whether this will be noticed, or monitoring the reactions of security personnel to the actions that would  occur during a real attack. The dry run is considered to be the heart of the planning stages of the terrorist attack. It is the method by which strengths and weaknesses in the plot are exposed to the terrorists, unforeseen obstacles can be detected, and the techniques are refined. Sometimes, multiple dry runs are conducted in an effort to perfect the ultimate attack. Suspicious signs. The following are suspicious signs a dry run may be occurring: