French marines opened fire on five unidentified drones that flew over a strategic nuclear submarine facility on Thursday evening, December 5, 2025. The incident occurred at approximately 7:30 PM local time at the Île Longue naval base in Brittany, which serves as the operational hub for France’s fleet of nuclear-powered ballistic missile submarines.
The marine infantry battalion responsible for base security detected the unauthorized aircraft and immediately activated counter-drone protocols. According to the regional gendarmerie, troops fired at the intruding devices, though authorities have not confirmed whether any of the drones were successfully neutralized.
France’s Nuclear Deterrent
The Île Longue facility houses France’s four nuclear ballistic missile submarines — Le Triomphant, Le Téméraire, Le Vigilant and Le Terrible. These submarines form the Force Océanique Stratégique (FOST), the backbone of France’s nuclear deterrent. At least one submarine remains constantly deployed at sea as part of France’s strategic defense posture.
The base, situated near the port city of Brest in western France, is protected by more than 120 maritime gendarmes working alongside marine security forces. It’s one of the most secretive and heavily defended places in France, occupied by approximately 2,400 personnel including civilian and military forces.
Defense Minister Catherine Vautrin confirmed that troops intercepted the overflight, though she did not specify the methods used against the aerial intruders. “Any overflight of a military site is prohibited in our country,” Vautrin said. “I want to commend the interception carried out by our military personnel at the Île Longue base.”
No Attribution Yet
Frédéric Teillet, the public prosecutor in Rennes, told Agence France-Presse that “no link with foreign interference has been established.” He said that marines had “fired a jammer and not a firearm” and that no drones had been shot down and no pilots identified.
Regional maritime authorities confirmed that critical infrastructure remained secure throughout the incident. Military prosecutors in Rennes opened a formal investigation into the breach on Friday.
The French Ministry of Defence has not attributed the incident to any specific actor or provided details about the origin of the drones. Officials have also declined to provide additional operational details, citing security protocols surrounding the nuclear deterrent program.
Part of a Broader Pattern
Thursday’s incident represents an escalation from previous unauthorized overflights in the region. Similar drone activity was reported over the nearby Crozon Peninsula in mid-November, though those aircraft did not penetrate military airspace.
The incident is also the latest in a recent spike in mysterious drone activity across EU member states. Several incidents have led to airport shutdowns and disrupted commercial flights, while others have been detected near military facilities.
Belgium recently experienced a wave of drone sightings over airports and military bases, including facilities believed to host U.S. tactical nuclear weapons. France responded by sending anti-drone teams to Belgium to assist with defense.
This is not the first time Île Longue has faced drone intrusions. In January 2015, drones were detected near the site over several days, though those flights were also determined not to present a characterized threat to the base’s security.
