A Ukrainian team operating naval drones defeated NATO forces in a competitive military exercise — a result that would have been unthinkable three years ago, and one that carries implications far beyond a single drill.
The exercise, known as Recognised Environmental Picture by Unmanned Systems (REPMUS), took place in Portuguese waters and brought together naval forces from across the Atlantic alliance. Ukraine, not a NATO member, was invited to participate. Its team, composed of operators with direct combat experience deploying unmanned surface vessels against the Russian Black Sea Fleet, didn’t just hold its own. It won.
According to Business Insider, Ukrainian officials confirmed that their drone operators outperformed teams from established NATO navies during the competitive portions of the exercise. The victory wasn’t a fluke or a narrow margin call. Ukrainian participants leveraged years of real-world operational experience — the kind that can’t be replicated in peacetime training — to dominate scenarios designed to test unmanned maritime capabilities.
That experience is hard-earned. Since Russia’s full-scale invasion in February 2022, Ukraine has waged what amounts to the world’s first large-scale naval drone war. Lacking a traditional navy capable of challenging Russia’s Black Sea Fleet head-on, Kyiv improvised. It built fleets of low-cost, explosive-laden unmanned surface vessels and used them to strike Russian warships, including the guided-missile cruiser Moskva, patrol boats, and landing ships. The campaign forced Russia to withdraw significant naval assets from Crimea — a strategic achievement accomplished without a single Ukrainian warship.
Now that asymmetric expertise is being tested against the alliance Ukraine hopes to one day join. And it’s winning.
The REPMUS exercises, hosted annually by the Portuguese Navy, have become one of NATO’s premier testing grounds for unmanned systems across air, surface, and underwater domains. The 2024 and 2025 iterations drew growing international participation as allied navies scrambled to integrate drone technology into their force structures. Ukraine’s inclusion reflects both a recognition of its battlefield innovations and NATO’s desire to learn from them.
What makes Ukraine’s performance so striking is the gap between resources and results. NATO navies operate with budgets that dwarf Ukraine’s defense spending. They have access to sophisticated command-and-control infrastructure, satellite communications, and decades of institutional doctrine development. Ukraine’s drone operators, by contrast, built their playbook under fire — often literally assembling vessels in makeshift workshops and deploying them against targets within days.
The competitive drills at REPMUS tested a range of unmanned maritime tasks: surveillance, target identification, coordinated swarm operations, and engagement scenarios. Ukrainian teams reportedly excelled in speed of decision-making and adaptability — two qualities forged in the chaos of actual combat operations. When scenarios shifted unexpectedly, Ukraine’s operators adjusted faster than their NATO counterparts, who were more accustomed to following predetermined procedures.
This shouldn’t surprise anyone who has studied how Ukraine fights. The country’s military culture has been transformed by three years of high-intensity warfare into something unusually flat, decentralized, and initiative-driven. Junior officers and enlisted operators routinely make decisions that would require senior approval in most NATO militaries. That cultural difference showed up clearly in the exercise results.
There’s a broader lesson here for Western defense establishments. NATO has spent years talking about unmanned systems. Publishing white papers. Running procurement programs. Standing up innovation offices. Ukraine has spent those same years actually fighting with drones — at sea, in the air, and on the ground — and iterating at a pace no peacetime military can match.
The gap between doctrine and practice is real. Several NATO navies are still in the early stages of integrating unmanned surface vessels into their fleets. The U.S. Navy’s Task Force 59, based in Bahrain, has experimented extensively with unmanned platforms in the Middle East, but even its efforts remain largely experimental. The Royal Navy has tested autonomous minehunting systems. France has invested in underwater drones. But none of these programs have been stress-tested the way Ukraine’s have — against a peer adversary actively trying to destroy them.
Ukraine’s success at REPMUS also raises uncomfortable questions about NATO’s readiness posture. If a non-member state with a fraction of the resources can outperform allied teams in the alliance’s own exercises, what does that say about the speed at which NATO is adapting to unmanned warfare? The answer, for many defense analysts, is: not fast enough.
The drone war in the Black Sea has already rewritten assumptions about naval power. A nation without a blue-water navy effectively established sea control over a significant portion of a contested body of water using weapons that cost a tiny fraction of the ships they targeted. A single Ukrainian maritime drone costs roughly $250,000. A Russian corvette costs hundreds of millions. The math is devastating.
And it isn’t just about cost. It’s about speed of production, speed of deployment, and speed of tactical adaptation. Ukraine has demonstrated that it can design, build, and field a new drone variant in weeks. Traditional naval procurement cycles in NATO countries measure new platforms in years, sometimes decades. The mismatch is glaring.
Ukrainian defense officials have been vocal about wanting to share their lessons with NATO allies. President Volodymyr Zelensky has repeatedly framed Ukraine’s war as a proving ground for technologies and tactics that the entire Western alliance will eventually need. The REPMUS results give that argument considerable weight.
Some NATO officials are listening. There have been increased bilateral exchanges between Ukrainian drone units and allied special operations forces. Several countries have sent observers to study Ukrainian unmanned operations firsthand. But translating observations into institutional change is slow work, particularly in large bureaucratic defense organizations resistant to abandoning legacy platforms and established doctrine.
The political dimension matters too. Ukraine’s strong showing at a NATO exercise bolsters its case for membership — or at the very least, for deeper integration into allied command structures. It demonstrates interoperability, tactical competence, and a willingness to operate within multilateral frameworks. For Ukrainian diplomats, a win at REPMUS is worth more than a dozen position papers.
But there are limits to what exercises can prove. Real combat involves friction, casualties, electronic warfare, and an adversary that adapts. Ukraine knows this better than anyone. The question is whether NATO can absorb Ukraine’s hard-won lessons without having to learn them the hard way itself.
The Black Sea drone campaign has already influenced military thinking worldwide. China is watching closely. So is Iran. Both countries have invested heavily in unmanned naval systems, and both see in Ukraine’s example a template for challenging conventional naval superiority at low cost. The proliferation implications are significant — and they extend well beyond the current conflict.
For NATO, the takeaway from REPMUS should be clear. The alliance’s most innovative unmanned naval force isn’t operating out of Norfolk or Portsmouth or Toulon. It’s operating out of Odessa. And it just proved it on NATO’s own turf.
Whether that provocation leads to genuine institutional change or simply another round of conference presentations and strategy documents will determine much about the alliance’s readiness for the next decade of maritime competition. Ukraine has shown what’s possible. The question now is whether NATO has the will — and the institutional agility — to keep up.
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