REPMUS 2026: Portuguese Navy conducts large scale counter-UxS exercise

Portuguese Navy Modernised M-class frigate Bartolomeu Dias (F 334) at Exercise REPMUS 26 on 22 September 2026. (Janes/Neil Dee)

The Portuguese Navy conducted a large scale counter-unmanned systems (C-UxS) test at NATO Exercise ‘REPMUS 26' (Robotic Experimentation and Prototyping with Maritime Unmanned Systems) which took place from 31 August to 25 September 2026 in Portugal.

Speaking to media at REPMUS 26 on 21 September 2026, Captain Caldeira de Carvalho, director of the Portuguese Navy's Operational Experimentation Centre (Centro de Experimentação Operacional da Marinha: CEOM) said that during the serial, undertaken on the night of 20 September 2026, the Portuguese Navy's Modernised M-class frigate Bartolomeu Dias (F 333) was escorted by approximately 20 to 30 unmanned aerial vehicles (UAVs) and unmanned surface vehicles (USVs). A simulated attack by over 60 USVs supported by UAVs (that were used to locate the frigate and guide the USVs) was in turn conducted against the frigate, Captain de Carvalho said.

In the serial, Bartolomeu Dias portrayed the role of a ship enforcing a NATO exclusion zone. During the exercise, opposition red and friendly blue forces were also swapped at times so as to gain greater experience in training, Captain de Carvalho said.

The scenario was not a tactical exercise, instead focusing on trialling prototypes, artificial intelligence (AI), and experimental doctrine and tactics, Captain de Carvalho said. Making mistakes and learning were part of this innovation. Planned next steps are expected to be a full exercise outside of the REPMUS experimentation, using manned and unmanned systems. Learnings from REPMUS will also inform the Portuguese Navy's future acquisition of USVs and UAVs, Captain de Carvalho added.