Suspected sabotage of frigate “Hessen” (Wilhelmshaven)

On Thursday, 20 February 2025, German authorities discovered a suspected sabotage attempt against the navy frigate Hessen while the ship was docked at the Marinearsenal (naval arsenal) in Wilhelmshaven. According to German public-broadcaster and newspaper investigations, several dozen litres of used oil were apparently to be introduced into the vessel's drinking-water system precisely as the system was being flushed during scheduled maintenance work.

The attempt was detected in time, and according to the reporting no actual contamination of the ship occurred. Investigators noted that, had the oil entered the system unnoticed, extensive and time-consuming cleaning would have been required, since the drinking-water system is essential to sustaining the crew on board.

The Federal Ministry of Defence confirmed a "possible security-relevant incident" at the naval arsenal in Wilhelmshaven, and police in Wilhelmshaven confirmed they were investigating a case involving a navy ship, as reported by tagesschau and buten un binnen. The Bundeswehr and police are treating the matter as a suspected sabotage case rather than an accident, with sources reportedly ruling out an inadvertent refuelling error.

The Hessen case followed an earlier suspected incident in mid-January 2025, in which metal shavings were reportedly placed in the propulsion system of the new corvette Emden and discovered during a check at a shipyard. Together the events fuelled concern about possible attacks targeting the German Navy.

Reporting consistently characterises the Hessen case as a suspected sabotage attempt under investigation, not a proven act. The Defence Ministry confirmed only a "possible security-relevant incident", and no perpetrator, motive or state attribution has been officially established. The cluster of similar incidents around the same period led officials and media to assess a heightened risk of deliberate interference with naval assets, consistent with concerns about hybrid threats. Absent confirmed findings, any link to a coordinated campaign remains an assessment rather than a confirmed fact.