PARIS — France has conducted the first test launch of its upgraded M51.3 submarine-launched ballistic missile (SLBM) from the nuclear-powered ballistic missile submarine Le Vigilant. The unarmed missile was launched off the coast of Finistère in Brittany as part of an acceptance trial following the submarine's major maintenance overhaul.
The missile, launched under Operation SMERTRIOS, carried no nuclear warhead or other payload. Its flight was tracked by French missile-testing assets, including the trials ship Monge, before it impacted in the North Atlantic several hundred kilometres from any coastline. The French Ministry of the Armed Forces said the test was conducted in strict compliance with France's international obligations.
French President Emmanuel Macron watched the launch from the multi-mission frigate Auvergne. He congratulated the DGA, CEA, ArianeGroup, Naval Group and French Navy, saying the test demonstrated France's technical capability and the credibility of its nuclear deterrent.
Macron also noted that France's defence budget is on a path to double compared with 2017 levels. He highlighted the construction of future strategic submarines and the programme launched this year for hypersonic manoeuvring strategic missiles for the airborne component of France's nuclear deterrent.
M51.3 Missile
The M51.3 is the third operational version of the M51 missile family and entered service in October 2025. Designed and produced by ArianeGroup under DGA supervision, it provides improvements in range, accuracy and missile-defence penetration compared with earlier versions.
The missile uses the newer TNO-2 oceanic nuclear warheads developed by the CEA. France does not officially publish its range, while open-source estimates for the M51 family put it at around 8,000–10,000 km or more. French officials have said the M51.3 can travel several hundred kilometres farther than earlier versions.
The missile is about 12 metres long, roughly 2.3 metres in diameter and weighs more than 50 tonnes at launch. It uses three solid-propellant stages.
France operates four Le Triomphant-class ballistic missile submarines, with each carrying 16 M51 missiles. The successful firing confirms Le Vigilant's ability to operate the M51 system after its periodic maintenance and repair period, known as IPER, clearing the way for its return to the operational deterrent patrol cycle. Le Terrible conducted a similar acceptance firing in April 2023 after its overhaul.
France's nuclear deterrent consists of sea- and air-launched systems, with its four ballistic missile submarines forming the core of the oceanic component. The country is also developing the M51.4, planned to provide further improvements in range, accuracy and penetration by around 2035, alongside the planned third-generation SSBNs.
The M51.3 test comes amid heightened security concerns in Europe, although the French ministry did not identify any specific country in connection with the launch.
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