The European Defence Agency (EDA) demonstrated that MARSUR, the EU's maritime surveillance network, can exchange data in real time with national command systems and NATO during a test off the coast of Portugal in September 2026.
The test took place at REPMUS — the Robotic Experimentation and Prototyping using Maritime Unmanned Systems exercise running from 31 August to 25 September. It is Europe's largest exercise of its kind, hosted by the Portuguese Navy alongside EDA and NATO.
Jürgen Scraback, Head of the Maritime Domain at EDA, said the REPMUS results marked "the first time this level of multi-domain integration has been proven live, rather than just on paper." It is a significant step toward a fully classified, EU Secret-level MARSUR network by 2028, he said. It also fills another EU capability gap to meet the Readiness 2030 agenda.
Launched under EDA's auspices, MARSUR is a federated network that gives European nations a shared, real-time naval picture of activity to help detect threats, complementary to NATO's own maritime surveillance architecture. MARSUR’s sophistication has accelerated markedly over the past two years, becoming the European Union’s eyes at sea. Fusing data from across EU navies, radar, satellites, and open-source feeds gives commanders the clarity required to respond to crises and threats.
REPMUS as the proving ground
Using a data-exchange standard implemented for the exercise, MARSUR ingested information made available by participating nations and systems, including information originating from unmanned systems as well as national and NATO sources, and distributed it within the MARSUR network.
High-level attention underscored growing interest in MARSUR's capabilities. Portugal's President António José Seguro received a briefing during REPMUS, as did Sweden's Chief of Navy, Rear Admiral Johan Norlén.
Many of the 23 participating EU nations also tested standard operating procedures for the MARSUR network and ran national scenarios reflecting individual maritime security priorities, including protection of underwater infrastructure and monitoring of so-called shadow fleet vessels used to evade sanctions.
Towards EU secret-level classification
The REPMUS results strengthen the case for a funding request, submitted under an EU Defence Project of Common Interest, to upgrade MARSUR to EU Secret-level classification. The plan would modernise 18 network nodes and integrate the system with the European External Action Service's secure operational network.
Subject to European Council approval later this year, work would begin in 2027, with a fully classified network operational by 2028. MARSUR currently operates at an unclassified, protected level; while technically ready for "EU Restricted" classification, the decision was taken to pursue EU Secret level directly.
User interface of the MARSUR system