M51

The M51 is a French submarine-launched ballistic missile built by ArianeGroup for the French Navy. It was designed to replace the M45 and was first deployed in 2010. The three-stage engine is derived from the solid propellant boosters of the Ariane 5, and each missile carries six to ten independently targetable TN 75 thermonuclear warheads. The design began in the late 1980s at Aérospatiale as the larger M5 and was renamed M51 in 1996 when development costs fell by 20 percent. The French government ordered the missile from EADS Space Transportation in December 2004, its first unarmed flight test took place on 9 November 2006, and the M51.3 upgrade, agreed in 2014 and 2016, entered service in late 2025, with a fourth version, the M51.4, contracted in 2025.