How a five-dollar gadget put a Dutch warship at risk for 24 hours, calling security into question

A Dutch air-defense frigate sailing with the NATO carrier strike group centered on France’s Charles de Gaulle was inadvertently exposed after a postcard containing a hidden Bluetooth tracker was mailed aboard, according to the Register, citing Dutch broadcaster Omroep Gelderland and Dutch defense officials. 

The vessel, HNLMS Evertsen, was reportedly trackable for roughly 24 hours after departing Heraklion, Crete, before the device was discovered and disabled.

The incident has raised fresh questions about operational security at sea, particularly as low-cost consumer devices can exploit nearby smartphones to transmit location data.

Because Evertsen was operating as part of a wider strike group in the Mediterranean, even the exposure of one escort ship could have helped adversaries infer the movements of the broader naval formation.

According to the reports, Dutch journalist Just Vervaart followed the mailing instructions published by the Dutch Ministry of Defense and concealed the tracker inside a postcard sent through military mail. The device then transmitted location signals from the ship for about a day, allowing the sender to follow the frigate’s route after it left Crete and headed in the direction of Cyprus.

Dutch defense officials said the tracker was found during mail sorting and taken offline. In response, the ministry changed its procedures, including banning the shipment of greeting cards containing batteries to the frigate and reviewing broader mail guidelines.

The episode underscored how an inexpensive commercial gadget can create a military vulnerability without anyone needing physical access to a warship in port. Reports on the incident said the loophole existed because packages were screened, while ordinary cards were not subject to the same checks.

The Dutch frigate incident suggests that the threat is no longer limited to what service members post themselves. A battery-powered tracker hidden in routine mail was enough to reveal the movements of a warship operating alongside one of Europe’s most prominent carrier groups in the eastern Mediterranean.