France test-fired an upgraded M51.3 strategic ballistic missile from the nuclear-powered ballistic-missile submarine (SSBN) Le Vigilant on 6 October 2026. The unarmed missile was launched off Finistère in western France and splashed down in the North Atlantic, several hundred kilometres from any coastline.
Submarine-launched ballistic missiles
A submarine-launched ballistic missile (SLBM) is a ballistic missile designed for launch from a submarine. An SSBN is a nuclear-powered submarine equipped to carry and launch ballistic missiles. France’s M51 system is deployed on its SSBN fleet as part of the country’s sea-based nuclear deterrent. The test, named Operation SMERTRIOS, was an acceptance firing after Le Vigilant completed a major mid-life refit, known in France as an IPER. It tested the submarine’s ability to operate the M51 missile system after the refit.
M51 missile system
ArianeGroup manufactures the M51 missile. The M51.3 variant entered operational service on 24 October 2025, following its first land-based flight test from Biscarrosse in November 2023. Its estimated range exceeds 9,500 kilometres. The M51.3 is designed to carry TNO-2 oceanic nuclear warheads. The variant incorporates improved accuracy and penetration capabilities against missile defences. The missile’s flight was tracked by the Directorate General of Armament’s missile test directorate, with the range instrumentation ship Monge also involved.
France’s nuclear deterrent
France’s nuclear deterrent includes a sea-based component supported by its SSBN fleet. The M51.3 test forms part of the modernisation of this deterrent, alongside the development of future ballistic-missile submarines. President Emmanuel Macron observed the launch from the multi-mission frigate Auvergne.
Important Facts for Exams
- The M51 is a French submarine-launched ballistic missile manufactured by ArianeGroup.
- Le Vigilant is a nuclear-powered ballistic-missile submarine in the French Navy.
- Biscarrosse was the site of the M51.3’s first land-based flight test in November 2023.
- Monge is a French range instrumentation ship used in missile testing.
The M51.3 entered operational service in October 2025. The October 2026 launch took place after Le Vigilant completed its mid-life refit.
