A Bluetooth tracker hidden in a postcard made it possible to track the location of a Dutch warship 24 hours a day

Dutch media tracked the movement of the naval frigate Evertsen for about 24 hours using a Bluetooth tracker hidden inside a postcard.

The device was only discovered later in military mail sorting, exposing a real security gap rather than a technical glitch.

The case showed that a low-cost gadget can reveal a warship’s location, highlighting weaknesses in military communications and mail handling.

The Dutch Navy said it would review its mail operations after the incident.