From looking at the 2013 owner's manual, pg 84, it is clear that a true anti-theft alarm is an option. The passive security system (not to be confused with an alarm system) works only with Ford anti-theft systems, according to the manual.
ANTI-THEFT ALARM (IF EQUIPPED) The system will warn you of unauthorized entry to your vehicle. The turn signal lamps will flash and sound the horn up to a total of 10 times when: • any door, the hood or the luggage compartment is opened without using the keypad, the remote control or the intelligent access transmitter (if equipped) • the ignition is turned on with an invalid key. Take all keys and remote controls to an authorized dealer if there is any potential alarm problem with your vehicle.