NATO’s REPMUS 2025 exercise in Portugal concluded in September, demonstrating an allied push to integrate innovative defense technologies, like drones and AI, for border defense following a series of provocative airspace violations by Russia drones access Poland, Denmark, and the Baltics.
The three-week drill featured Ukraine’s frontline forces on the “red team,” providing tactical expertise, while defense companies tested counter-drone technologies, such as jamming systems and a hydrogen-powered blimp designed for electronic warfare.
Soldiers, scientists, and defense corporations converged at the Portuguese Navy Operational Experimentation Centre in Tróia for defensive technology. Exercises included naval heritage with new digital technology: sea and air drones, virtual reality (VR) headsets for commanding operations, and advanced mapping systems. Even a nuclear submarine crossed the nearby seas.
The exercise takes place as tensions simmer beneath the European defense and security policy, with airspace interruptions already compelling NATO and accelerating central European defence cooperation.
Training With Drones
REMPUS, which stands for Robotic Experimentation and Prototyping using Maritime Unmanned Systems, is a NATO supported military project focused on experimenting with innovative defense technologies and improving coordination between allies.
In 2025, drones were at the center of NATO training. Ukraine was a first-time participant in joining the “red” team of the opponents with 61 drones, 57 unmanned surface systems, and one ground robot.
“The participation of Ukraine is very important because they bring to us the procedures and the tactics that they are doing on the frontline,” Captain Valter de Bulha Almeida of the Portuguese Navy told Euronews Next.
Daily jamming exercises simulated battlefield conditions, a direct echo of the NATO Russia border military drills and recent drone invasions across Europe.
According to Aljazeerar, in early September, unauthorized drones breached Polish and Danish air space, closing airports and rattling NATO allies. Estonia and Romania also reported breaches, with Poland lodging concerns under NATO’s Article 4 when Russian drones were downed during a fierce aerial attack on Ukraine.
“The repeated violations of our airspace are unacceptable. The message is clear: Russia is testing the EU and NATO. And our response must be firm, united and immediate,” EU Defense Commissioner, Andrius Kubilius, said.
Therefore, it was agreed to build a “drone wall” along borders with Russia and Ukraine, in a joint effort with Kyiv and Baltic states to intercept attacks. For the Ukrainian Defense Minister, this project is a “a fundamentally new defense ecosystem,” part of wider NATO European defense preparations.
Moreover, the European Security and Defense has reported that the sense of urgency has been felt in Scandinavia too, where Sweden and Denmark reinforced their stances in response to incursions near Copenhagen and across the Gulf of Finland. Meanwhile, NATO launched its “Eastern Sentry” mission on 12 September, employing “both conventional capabilities and new technologies” to defend its eastern side.
Tech Firms Bring Future to War Zones
Defense firms and startups were involved at REMPUS. Tróia’s free technology zone – 2,600 square kilometers of air and sea space- allowed testing that would be restricted elsewhere.
French firm Akheros demonstrated an AI-immune jamming drone plug-in, and Germany’s Rheinmetall unveiled its HERO kamikaze drone — among the Russia NATO border military buildup consistent components. Finnish company Kelluu launched its hydrogen-powered drone blimp engineered to counter constant jamming in Russian proximity. These defense technology solutions are only part of a greater endeavor to integrate AI and automation into readiness for battle.
While NATO defense spending grows, particularly after NATO allies reaffirm commitment to collective defense despite trump’s skepticism, investor attention is also shifting.
“We need to benefit from the advances that technology innovation is bringing and move into a cutting-edge moment,” NATO maritime expert Luis Brito said.
From Europe’s anticipated drone wall to NATO’s “Eastern Sentry,” the region is racing to deploy innovative defense technologies against increasing threats.
With defense innovations and end ultimate defense technologies entering service, allies see these capabilities as critical for resistance modernization, a future when willingness is not merely measured in soldiers, but in systems.
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