An M51.3 submarine-launched ballistic missile with no nuclear charge was fired off Finistère, in western France, on Tuesday, Oct. 6, 2026, fired by the French Navy’s ballistic missile submarine Le Vigilant. France’s Ministry of the Armed Forces said the shot was an acceptance firing, the test that closes out the submarine’s periodic maintenance and repair period. The missile came down in the North Atlantic, several hundred kilometers from any coast.
The firing was a check on the boat as much as the missile. Le Vigilant’s major overhaul began in autumn 2023, and the shot was meant to show the submarine could again operate its strategic weapon system.
The ministry’s release of Oct. 6, 2026, titled “Missile M51.3: a successful acceptance firing from the SSBN Le Vigilant” (translated by Combat Rated), says the launch was carried out as part of an operation it names SMERTRIOS. “The missile, carrying no nuclear charge, was fired off Finistère,” the ministry wrote, and the firing came “at the end of its periodic unavailability for maintenance and repairs (IPER).” The purpose, in the ministry’s words: “It makes it possible to validate the submarine’s capacity to operate its weapon system.” All translations from the French are by Combat Rated.
Tracked by the test ship Monge
France’s defense procurement agency followed the flight from launch to impact. “Its trajectory was followed throughout its flight phase by the assets of the Directorate General of Armament,” the release says, specifically its missile-test branch, DGA Essais de missiles, “notably by the trials and measurement ship Monge.” The ministry located the impact zone in the North Atlantic, “several hundred kilometers from any coast.” President Emmanuel Macron watched the launch from the frigate Auvergne, the ministry said.
The release does not describe the missile’s range or the flight’s duration, and it does not call the shot a first of any kind. The ministry frames it strictly as a validation of the submarine after maintenance.
Four million hours in dock at Brest
The maintenance period behind the firing was long and heavy. Naval Group, the shipbuilder that carried out the work, said in a July 18, 2025 press release issued from Brest that Le Vigilant’s IPER “began in autumn 2023 at the Île Longue operational base” (translated by Combat Rated). The first step was the removal of the weapons and of the fuel elements from the submarine’s nuclear reactor.
The boat then spent 18 months of what Naval Group called intensive work in Basin 8 at the Brest naval base. The company put the totals at 4 million hours of work, 45,000 lines of preventive maintenance and 34,000 equipment inspections, with more than 1,000 people mobilized, per the same release. The work covered preventive and corrective maintenance on all of the submarine’s systems. On July 18, 2025, Le Vigilant returned to Île Longue for the final phase of the maintenance period, the release said, and the Oct. 6, 2026 firing marks the end of that period in the ministry’s account.
The third version of the M51
The weapon itself had been in operational service for less than a year. The ministry’s Oct. 6 release says the M51.3 “entered operational service on Oct. 24, 2025,” equipped with new oceanic nuclear warheads designated TNO-2. Naval News, reporting the service entry on Oct. 29, 2025, said the missile “offers improved range, accuracy, and penetration capabilities” and will be deployed aboard the French Navy’s Le Triomphant-class ballistic missile submarines.
ArianeGroup, the missile’s builder, describes itself as the industrial prime contractor for the M51 on behalf of the DGA, covering design, production, maintenance, in-service support and decommissioning. In its announcement on the M51.3 entering service, the company said the M51.3 is “the third version” of the M51 strategic ballistic missile, that the M51.1 and M51.2 remain in service, and that the M51.3 “will gradually replace them.” ArianeGroup said the M51.3 completed its qualification flight in November 2023 from the Ballistic Launch Base at the DGA’s missile test range in Biscarrosse, southwest France.
The program is already working on its successor. Naval News reported in the same October 2025 article that the DGA awarded ArianeGroup a contract for the fourth version, the M51.4, in September 2025.
Top image: A French Navy Le Triomphant-class ballistic missile submarine at sea off Brest on Oct. 15, 2024. The class includes Le Vigilant; the boat shown is not identified. Image Credit: Marine nationale — Licence Ouverte / Wikimedia Commons
This article was produced with the assistance of AI and reviewed by Combat Rated editors prior to publication.