France Prepares First Submarine-Launched Nuclear-Capable Missile Test in Three Years

France is preparing its first submarine-launched ballistic missile test in three years, with the nuclear-powered ballistic missile submarine Le Vigilant expected to fire the new M51.3 during a long-range trial over the Atlantic, according to French outlet Ouest-France on October 5.

Strategic weapons analyst Étienne Marcuz said the missile is expected to travel roughly 4,700 kilometers, or about 2,920 miles, although that distance is well below the weapon’s estimated maximum range.

The M51.3 will be launched without a nuclear warhead from waters off France’s Finistère coast, where maritime restrictions have already been imposed through October 21.

The test comes after Le Vigilant completed an extensive maintenance period that began in fall 2023 at France’s Île Longue strategic submarine base.

The overhaul included work on the vessel’s nuclear reactor, weapons systems, and other critical equipment. French ballistic missile submarines typically undergo sea trials after such major maintenance, with an M51 launch serving as one of the most important checks that the submarine’s strategic weapons complex is fully operational.

A similar test was carried out by Le Terrible in April 2023 following its own major refit. This time, however, France will be testing the newest operational version of its sea-based deterrent missile.

The M51.3 officially entered operational service in October 2025. Compared with earlier versions, the new variant is reported to offer improved range, greater accuracy, and better ability to penetrate missile defenses. It is also designed to carry France’s new TNO-2 nuclear warhead.

France conducted the first qualification launch of the M51.3 in November 2023 from a land-based test facility at Biscarrosse. That missile was also unarmed and flew toward the Atlantic Ocean.

The M51.3 is a three-stage, solid-fueled submarine-launched ballistic missile developed as the latest evolution of France’s M51 family. Paris does not disclose its exact performance, but earlier M51 versions have been estimated to reach approximately 8,000 to 10,000 kilometers, or roughly 5,000 to 6,200 miles, at speeds of up to Mach 25.

Previous M51.1 and M51.2 missiles could carry multiple thermonuclear warheads with individual yields estimated at roughly 110 to 300 kilotons. The M51.3 is believed to retain broadly similar dimensions to its predecessors, measuring around 12 meters long, 2.3 meters in diameter, and weighing roughly 52 metric tons.

The missile is also expected to become the primary strategic weapon of France’s future SNLE 3G ballistic missile submarines, which are scheduled to begin replacing the current Le Triomphant-class fleet after 2035. ArianeGroup develops and manufactures the M51 family.

Earlier, France’s Air and Space Force has rehearsed one of the country’s most consequential military missions: breaking through hostile defenses and delivering a nuclear-armed missile to a precise launch point using Rafale fighters.

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