On the night of December 4, 2025, French navy personnel stationed at the Île Longue submarine base in Brittany found themselves in a tense standoff with the unseen: five unidentified drones appeared overhead, prompting immediate defensive action. According to Agence France-Presse (AFP), troops tasked with safeguarding the base, which houses France’s nuclear-powered ballistic missile submarines, opened fire on the intruding aircraft. It was an unsettling moment for a site that represents a cornerstone of France’s nuclear deterrent, and for good reason—the base is home to the Le Triomphant class submarines, a critical asset in France’s continuous-at-sea nuclear strategy.
The incident, which occurred around 19:30 local time, set off alarm bells not only in France but across Europe. As reported by AFP and corroborated by multiple European outlets, the military prosecutor’s office in Rennes swiftly launched an investigation into the airspace breach. While it remains unclear whether the drones were shot down, French authorities confirmed that anti-drone fire and jamming techniques were employed in efforts to neutralize the threat. Frigate Captain Guillaume Le Rasle, speaking on behalf of the maritime prefecture, described the drones as lightweight and unarmed, emphasizing that they did not pose a significant threat to the base’s critical infrastructure.
This was not an isolated event. The overflight at Île Longue is just the latest in a troubling series of drone incursions near sensitive military and defense sites across Europe. In recent months, similar sightings have been reported over strategic facilities in Belgium, Germany, Denmark, Norway, and the Netherlands. According to The i Paper, these incursions have included flyovers at NATO training bases, energy assets, and even defense manufacturing plants such as Thales’ Évegnée Fort facility. The pattern has grown so persistent that European leaders are now on high alert, with suspicions increasingly directed toward Moscow.
Drone incursions are not just a technical nuisance—they’re a strategic headache. As Martin Melia, a former British Army Lieutenant Colonel with expertise in Intelligence, Surveillance, and Reconnaissance, told The i Paper, these unmanned aerial vehicles (UAVs) allow aggressors to "stand off" from their targets, operating "beyond the visual line of sight" and causing disruption with a high degree of deniability. "It’s an effective form of sabotage and influence activity," Melia explained, noting how even a small drone can have a "disproportionate effect" by grounding flights, disturbing military exercises, or simply sowing public anxiety.
The origin of the drones over Île Longue remains a mystery, and French authorities have yet to comment publicly on who might be responsible. However, the broader context is hard to ignore. The i Paper and other European sources have reported that many recent drone flights near sensitive sites are believed to have been launched from Russian-linked cargo ships in the North Sea and Irish Sea. These so-called "shadow fleet" vessels, allegedly operated by the Kremlin, are thought to provide mobile platforms for drone launches, helping to obscure their true point of origin and bypass international regulations.
This strategy of using drones as tools of hybrid warfare—aggressive acts that fall short of open conflict—has become increasingly common. Most incidents have not been officially attributed to state actors, but European leaders have not minced words about their suspicions. After a spate of drone overflights in Germany’s Schleswig-Holstein region in October, Chancellor Friedrich Merz stated unequivocally, "We suspect that Russia is behind most of these drone flights." His remarks echoed a growing consensus across NATO capitals that the uptick in drone activity is part of a broader campaign of intimidation and intelligence-gathering by Moscow.
The shadowy nature of these incursions makes them especially difficult to counter. In February 2025, The i Paper revealed that individuals with links to Russian military and intelligence organizations had traveled to locations near top-secret UK air bases—including RAF Mildenhall—on days when suspicious drones were observed overhead. Meanwhile, the Russian vessel Yantar was recently confronted by British forces after it was suspected of deploying drones near undersea communication cables connecting Ireland and the UK.
But it’s not just the UK and Germany facing these challenges. In France, the Crozon peninsula—close to Île Longue—experienced a drone overflight in mid-November, though it did not violate the military zone. And just days before the Île Longue incident, four "military-style" drones reportedly breached no-fly zones and approached the flight path of Ukrainian President Volodymyr Zelenskyy’s plane as he landed in Dublin. According to UK intelligence sources cited by AFP, those drones were likely launched from cargo ships in the Irish Sea, once again highlighting the international and maritime dimensions of this emerging threat.
In response to these provocations, European militaries are stepping up their defenses. The UK granted troops authority in October to shoot down suspect drones hovering over sensitive sites, mirroring the robust response seen at Île Longue. Meanwhile, France continues to modernize its strategic deterrent. In October, the French military unveiled an upgraded M51 submarine-launched ballistic missile, boasting improved range, precision, and penetration capabilities—a clear signal that Paris is not standing still in the face of evolving threats.
France’s nuclear deterrent, unique within the European Union, relies on both its submarine fleet and an aerial component consisting of Rafale fighter jets equipped with nuclear-tipped cruise missiles. French doctrine mandates that at least one nuclear-armed submarine is always on active patrol, ensuring a credible second-strike capability. The importance of securing the bases that house these assets cannot be overstated. As Frigate Captain Le Rasle reassured the public, "The drones did not represent a significant threat to the infrastructure," but the military’s swift action and the ongoing investigation by the Rennes prosecutor’s office reflect the seriousness with which these incursions are treated.
The broader trend is clear: drone technology, once the preserve of hobbyists and commercial interests, has become a potent tool in the gray zone between peace and war. Whether used for surveillance, sabotage, or psychological operations, drones offer adversaries a cheap and deniable means to probe defenses and test responses. As incidents like the one at Île Longue become more common, European militaries are being forced to adapt, investing in new detection, jamming, and counter-drone systems to protect their most sensitive sites.
For now, the skies over Brittany are quiet once more, but the episode serves as a stark reminder that the battle for security in the 21st century is as much about unseen threats as visible ones. As France and its allies confront the challenge of hybrid warfare, vigilance, rapid response, and international cooperation will be more essential than ever.