NATO has concluded the REPMUS/Dynamic Messenger 2025 exercise in Troia and Sesimbra, Portugal, with a stated aim of advancing the integration of unmanned systems into maritime operations.
The exercise combined REPMUS (robotic experimentation and prototyping with maritime unmanned systems) with Dynamic Messenger, part of NATO’s operational experimentation series.
Hosted by the Portuguese Navy and co-organised by NATO's Allied Maritime Command (MARCOM) and Allied Command Transformation (ACT), the drills tested new capabilities across naval mine warfare, underwater operations, countering unmanned vehicles, and command and control.
Spanish Navy Captain Julio Hernandez, MARCOM’s Assistant Chief of Staff for Exercises, said the event, “showcased the power of collaboration”. He added, “Collaboration with academia and industry through joint experimentation is vital for allied and partner nations to accelerate innovation at the speed and scale needed to maintain military and technological superiority.”
NATO confirmed that more than 3,800 participants and 260 systems from 22 nations took part, joined by observers from 13 additional countries. Ukraine’s navy, for the first time, led the opposing force, which NATO described as a milestone reflecting Ukraine’s increasing involvement in alliance exercises.
Trials included the deployment of France’s A9-M autonomous underwater vehicle and pivot remotely operated vehicle for mine countermeasures and seabed surveys.
NATO’s Centre for Maritime Research and Experimentation also introduced new systems for information sharing and early warnings of potential threats to critical underwater infrastructure.
The event was supported by MARCOM, the Portuguese Navy and NATO’s Joint Analysis, Training and Education Centre with Ukraine. NATO said the exercise also provided operational lessons drawn from Ukraine’s frontline experience.