On the night of September 9–10, 2025, somewhere between 19 and 23 Russian surveillance drones — identified variously in source reporting as Gerbera or Shahed variants — crossed into Polish airspace during a large-scale attack on Ukraine. Dutch F-35s shot down three or four of them. Airports closed. NATO convened. The incident was, by the alliance's own count, the most significant airspace violation by a Russian platform since Moscow's 2022 invasion — and it was not an isolated probe.

Within ten days, Russian military fighters had violated Estonian airspace for 12 minutes over the Gulf of Finland, and a single drone had entered Romanian airspace, scrambling fighter jets in Bucharest. Taken together, the September events reframed what had been a slow accumulation of debris, wayward munitions, and surveillance overflights into something that looked more like a deliberate pattern. By NATO's count, the alliance has now logged eleven documented drone violations of member-state airspace since 2022, with the pace accelerating sharply in 2025.

The Cheap-Drone Problem and the Expensive-Response Trap

The core dilemma is economic. Individual Russian attack drones can cost as little as €257. The surveillance drones overflying Poland are unarmed platforms — but they require a response, and the cheapest credible response NATO has routinely fielded is an F-35 with an air-to-air missile. As Col. Mark McLellan, assistant chief of staff operations at NATO Allied Land Command, framed it bluntly: intercepting surveillance drones with fourth- and fifth-generation fighters is a lot cheaper than flying an F-35 — but it isn't cheap.

Romania has experienced at least 28 drone incursions since 2022; 15 occurred in 2026 alone. In May 2026, a Russian drone crashed into an apartment building in Galați, injuring two civilians. Lithuania experienced its first civilian shelter response to a drone incursion that same month, when a platform near the Belarus border prompted residents to seek shelter. At least ten European countries — Poland, Latvia, Lithuania, Estonia, Moldova, Finland, Denmark, Belgium, Bulgaria, and Greece — have reported sightings or confirmed incursions. As analyst Jennifer Kavanagh wrote in War on the Rocks, drones, missiles, and other debris have landed in Poland and Romania several dozen times since the invasion began.

The cost asymmetry has been clear for years. The institutional response is only now catching up.

Eastern Sentry: NATO's Immediate-Term Answer

Two days after the Polish incident, NATO Secretary-General Mark Rutte announced Operation Eastern Sentry. The operation is modeled structurally on Baltic Sentry, which NATO launched in January 2025 following critical undersea infrastructure incidents in the region. Contributing nations committed hardware quickly: Denmark provided two F-16s and one anti-air warfare frigate; France committed three Rafale jets; Germany contributed four Eurofighters. Gen. Alexus G. Grynkewich noted that the Polish airspace violation is not an isolated incident and impacts more than just Poland.

Eastern Sentry runs alongside NATO's existing multinational battlegroup posture — nine battlegroups across Bulgaria, Estonia, Finland, Hungary, Latvia, Lithuania, Poland, Romania, and Slovakia, with forces scalable to brigade size when conditions require. But the air and drone layer is where the operational gap has been most visible, and that's where the most interesting new hardware is appearing.

The American Merops counter-drone system is being deployed to Poland, Romania, and Denmark. Merops is compact enough to fit in the bed of a midsize pickup truck and is AI-guided to operate when satellite and electronic communications are jammed — a deliberate design choice for the contested electromagnetic environment Russia has demonstrated in Ukraine. Brig. Gen. Thomas Lowin described its operating concept as flying drones against drones, either engaging hostile UAVs directly or cueing ground and air forces. The system is expected to require two to five years for full deployment across the eastern flank.

The EU's Longer Bet: A 2,000-Kilometer Corridor

Operation Eastern Sentry addresses the immediate interception problem. The European Union's parallel initiative is aimed at the detection and persistent-monitoring gap that made those incursions possible in the first place.

The European Parliament Think Tank's October 2025 report identified two EU flagship projects carrying special urgency in the Defence Readiness Roadmap 2030: the Eastern Flank Watch and the European Drone Defence Initiative, collectively referred to as the European Drone Wall. The proposed architecture would stretch more than 2,000 kilometers — from Finland's Arctic border south to Romania's Black Sea coast — integrating radar networks, acoustic sensor arrays, electronic warfare systems, command-and-control architecture, and defensive weapons platforms, with directed-energy weapons designated as a future layer.

Eight nations anchor the project: Estonia, Latvia, Lithuania, Finland, Poland, Romania, Bulgaria, and Ukraine. EU Defense Commissioner Andrius Kubilius was direct about the baseline: We do not have the capability to detect [drones], or it is very limited. His cost estimate for closing the detection and interception gap across Poland, Lithuania, Estonia, and Latvia was approximately €1 billion.

Ukraine's inclusion is not merely symbolic. Kyiv operates thousands of acoustic sensors and effective command-and-control systems for drone tracking — capabilities Europe currently lacks and intends to learn from. The EU has separately allocated €6 billion from immobilized Russian sovereign assets toward Ukraine's drone production under the Drone Alliance framework, creating an intertwined logic: Europe funds Ukrainian drone manufacturing while studying Ukrainian counter-drone methods. Poland's national East Shield program and the Baltic states' Baltic Defence Line fortification project run as complementary national-level efforts alongside the multinational drone wall.

Timelines are ambitious. The European Drone Defence Initiative is targeted for initial operational capacity by end of 2026, full functionality by end of 2027. The Eastern Flank Watch is expected to be fully operational by end of 2028. Coordination frameworks among member states are to be agreed in spring 2026, with annual defence readiness reports to the European Council mandated each October.

Who's In, Who's Skeptical, and What Critics Say

The political geometry of the drone wall is not simple. Frontline advocates are predictable: Poland, Estonia, Latvia, Lithuania, and Finland have pushed hardest for the architecture and the fastest possible timeline. France, Germany, Italy, and Greece have been identified as skeptical states in EU governance discussions, with concerns centering on Brussels acquiring prerogatives that member states consider national sovereign territory.

The substantive critiques are harder to dismiss. The EP Think Tank's analysis included expert voices arguing that the Drone Wall addresses consequence management rather than deterrence — that building a sensor and interception barrier does not obviously close the underlying strategic gap. Kavanagh's War on the Rocks analysis made an adjacent point: that Putin's apparent aim is to expose the gap between Europe's rhetoric and its actual military readiness, and that the drone incursions may be less about intelligence gathering than about probing reaction times and the cost asymmetry a 2,000-kilometer sensor wall does not obviously resolve.

The technology maturity questions are real. Interoperability standards across eight national sensor networks haven't been finalized. The spring 2026 coordination deadline has passed without public confirmation of agreements. The Merops rollout carries a two-to-five-year window that runs well past the EU's stated 2027 full-functionality target. And the directed-energy weapon layer — potentially the most cost-effective solution for high-volume drone threats — remains a future capability, not a near-term one.

What Europe has built, as of mid-2026, is a credible institutional commitment and a partially deployed interception layer, set against a threat environment that is worsening faster than the sensor infrastructure can mature. Whether the drone wall becomes a genuine deterrent or a well-documented capability gap depends largely on how fast the coordination agreements actually close — and whether European defense procurement can move at a pace the threat environment requires.

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