The French Defence Procurement Agency (DGA) has awarded ArianeGroup a contract to design and produce the fourth version of the M51 submarine-launched ballistic missile (SLBM) known as “M51.4”. The M51.4’s enhanced range, precision and penetration capabilities will reinforce the credibility of France’s oceanic nuclear deterrent in response to evolving threats.
On August 28, 2025, the French Defence Procurement and Technology Agency (DGA) awarded ArianeGroup the contract to design and produce the fourth version of the M51 strategic ballistic missile (M51.4).
“This contract coincides with the entry into service of the M51.3, the missile’s latest version, and the acceleration in production at ArianeGroup in line with the agreed schedule,” comments Vincent Pery, Director of Defence Programs at ArianeGroup. “On behalf of ArianeGroup and all the teams, I would like to thank DGA for its renewed confidence in our highly strategic expertise and capabilities, which are vital to France’s Strategic Oceanic Force.”
The M51.4’s enhanced range, precision and penetration capabilities will reinforce the credibility of France’s oceanic nuclear deterrent in response to evolving threats.
The contract marks the start of design and then production of the M51.4, ensuring ongoing activity for ArianeGroup and hundreds of partner companies in the coming years. This major program will also serve as a driver of transformation, by incorporating innovative technologies, methods and approaches, in order to meet the ambitious technical and economic objectives.
ArianeGroup has been industrial prime contractor for France’s Strategic Oceanic Force (FOST) M51 strategic missile on behalf of DGA. In this role, ArianeGroup is active across the program’s lifecycle, including design, production, maintenance and in-service support, as well as end-of-life decommissioning and dismantling.
The M51 is the new generation intercontinental SLBM which started replacing the M45 in 2010. Each missile carries six to ten independently targetable (MIRV or Multiple Independently targeted Reentry Vehicle) TN 75 thermonuclear warheads. TN 75 are being replaced with the new Tête nucléaire océanique (TNO or oceanic nuclear warhead) warheads since 2015. These new warheads are reported to be maneuverable (MARV or Maneuverable Re-entry Vehicle) in order to avoid potential ballistic defenses. The TNO has a yield that is estimated to be greater than or equal to the yield of the TN 75 warhead, 150 kilotons of TNT (kt) with a CEP (circular error probability) of 150 meters.
The three-stage engine of the M51 is so good that it served as base to develop the solid propellant boosters of the European Ariane 5 space rocket. Open source data indicates an M51 weight of 52,000 kg, a length of 12.0 m and a diameter of 2.3 m. M51 operational range is reported to be 8,000 to 10,000 km with a speed of Mach 25.
The first test launch of an M51 ballistic missile was successfully carried out at Centre d’essais de lancement de missiles (CELM) in Biscarosse, France, on November 9, 2006. The sixth missile test carried out on May 5, 2013, ended in failure. The latest M51 tests in September 2015, July 2016, June 2020 and April 2021 and April 2023 were all successful.
The French military announced it successfully test-fired a new submarine-launched ballistic missile (SLBM) on 18 November 2023, from a land-based test facility. This was first ever launch of the M51.3 SLBM.
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