The Île Longue facility houses France's four nuclear ballistic missile submarines and provides maintenance for the vessels that form the basis of the country's nuclear deterrent.
French marines opened fire on five unidentified drones that flew over a strategic nuclear submarine facility on Thursday evening, military officials confirmed on Friday.
The incident occurred at approximately 7:30 p.m. 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 unauthorised aircraft and immediately activated counter-drone protocols, firing multiple rounds at the intruding devices, according to the regional gendarmerie.
A comprehensive search operation was launched following the engagement. Authorities have not confirmed whether any of the drones were successfully neutralised.
The Île Longue facility houses France's four nuclear ballistic missile submarines — Le Triomphant, Le Téméraire, Le Vigilant and Le Terrible — and provides maintenance for the vessels that form the basis of the country's nuclear deterrent.
At least one submarine remains constantly deployed at sea as part of France's strategic defence 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, according to domestic media reports.
Defence 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 specific actor named yet
Regional maritime authorities confirmed that critical infrastructure remained secure throughout the incident.
Military prosecutors in Rennes will open a formal investigation into the breach on Friday, officials said.
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 programme.
Thursday's incident represents an escalation from previous unauthorised 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.
Meanwhile, Russia has been involved in a number of airspace violations, notably in Estonia and Poland.