A laser-like focus on shared data standards to boost interoperability, and Ukrainian fighters leading “Red Team” forces in operational exercises testing uncrewed systems were among the key takeaways from the REPMUS/Dynamic Messenger 2025 Media Day.
Navy Leaders was present in Troia, Portugal today (Tuesday) to learn what progress has been made by NATO allies and partner nations across the course of the near month-long exercises running until September 26.
The Portuguese-led REPMUS exercise (Robotic Experimentation and Prototyping Augmented by Maritime Unmanned Systems), now in its 15th iteration, is the world’s largest experimentation event focused on uncrewed systems.
And this year it has been run in conjunction with NATO’s Dynamic Messenger (DYMS) 2025, lending an added layer of operational exercises (OPEX) to the experimentation offered by REPMUS.
Led by Allied Maritime Command (MARCOM), DYMS is part of NATO’s OPEX series aimed at supplying the opportunity to test and evaluate new technologies in a real-world environment and helping forces gain and maintain an operational edge.
As in previous years REPMUS/DYMS has again been run out of the Portuguese Navy Operational Experimentation Centre (CEOM) in Troia, with additional MCM activities at nearby Sesimbra. CEOM Director Captain Nuno Palmeiro Ribeiro remarked: “REPMUS reflects the reality we all face… It allows NATO and partners and commercial companies the chance to test interoperability, integration and innovation in a real-world environment.”
This year’s activities have been larger and more complex than ever, featuring a total of 37 countries (up seven from last year), no fewer than 276 individual uncrewed systems above, on and below the water, and around 3,700 participants.
For the first time the tactical operational elements of the exercise have been split into “Red” and “Blue” teams pitted against one another, and in another first, teams from the Ukraine have been heading up the “Red” forces to help take advantage of their battle-won insights and skills.
The Ukrainians have also been operating some of their own uncrewed air and surface assets, including the Magura V7 USV, as part of the OPEX serials.
Exercise Task Group Commander Captain Valter Bulha de Almeida explained the focus had been on taking an operational approach to experimentation and focusing on Tactics, Techniques, and Procedures (TTP) development, and integrating MUS into them.
Asked if the Ukrainian Red Team had been winning the drills, he said: “For me, the question is not who is winning: the important thing is developing the tactics, and I can guarantee we are learning a lot.”
One of the benefits of running DYMS alongside REPMUS this year has been the wider opportunities for OPEX serials featuring a wide range of assets. This year, a U.S. Navy submarine has also taken part, the USS New Mexico, which provided a rare chance to pit the American boat against its Portuguese counterpart in a two-day ASW exercise.
MARCOM Assistant Chief of Staff for Exercises Captain Julio Hernandez of the Spanish Navy commented: “With the Dynamic Messenger part, we are talking about operational advantage… a step forward in the OPEX process. We are trying to provide an operational environment for unmanned systems.”
He added: “We offer NATO and its allies a unique opportunity to explore advanced technologies in robotics,” describing the work being done over the past weeks as “the first exposition of emerging doctrines” taking in uncrewed assets in both surface and undersea warfare.
Another key focus of both exercises this year has been the drive to fully develop STANAG 4817, a standardised set of NATO data protocols that will ensure uncrewed assets from every participating nation can communicate, interact with each other, and contribute to the Common Operational Picture. This is a vital component necessary for progress towards the wider aim of seamless interoperability between allied NATO forces.
Joao Alves, Principal Scientist and Programme Manager for NATO’s CMRE research centre in La Spezia, Italy, explained: “STANAG 4817 will enable interoperability via a shared common data infrastructure… We have been asking ourselves: ‘Does this cover everything that we need it to cover?’”
He added that included not only real-time and near-real-time data inputs and command and control (C2) functions, but also the ability to re-task assets mid-mission, as well as data maintenance, cataloguing and analysis.
A packed Media Day took in all the above, and much more: other highlights included tours of “Virtual Ship” control rooms at CEOM, and meeting NATO DIANA start-up firms gaining valuable operational experience as part of the alliance’s initiative to support and drive innovation.
They also included a trip on board the Portuguese Navy Offshore Patrol Vessel NRP Figueira Da Foz to Sesimbra, witnessing some of the UUV and USV assets involved in the exercises in the water, and briefings on the employment of UxVs in MCM warfare.
Navy Leaders will be publishing more details of these aspects of an insight-packed day in the weeks and months ahead.