If you're worried about terrorism, here's a bigger threat to lose sleep over: an all-out cyber attack.
Suddenly, the electricity goes out at the office. Cellphone networks and the Internet have also gone black, along with subways and trains. The roads are jammed because traffic lights aren't working. Credit cards are now just worthless bits of plastic, and ATMs are nothing but hunks of metal. Petrol stations can't pump petrol. Banks have lost records of depositors' accounts.