Foreign intelligence, security services, terrorists, and criminals use surveillance for operational preparation prior to taking action.
The main terrorist threat to a traveler is that of being at the wrong place at the wrong time and becoming an inadvertent victim of a terrorist act.
Be observant and pay attention to your sixth sense. If you get the funny feeling that something is not right or that you are being watched, pay attention! Report your suspicions or any information to the general manager of the local affiliate or your embassy or consulate just in case something does occur.
If you have reason to believe that you are under surveillance, continue to act naturally.
Do not try to slip away, lose, or embarrass the surveillance as this may anger and alert them. It also may cause them to question whether you are, in fact, just a business person.
In your hotel room, do not play investigator and start looking for electronic listening devices. Ensure that you do not say or do anything in your hotel room that you would not want to see printed on the front page of The New York Times.
