5,200-ton nuclear attack submarine built to hunt enemy warships rolls off production line

France has just rolled out its fifth next-generation nuclear attack submarine (SSN), ready for final fitting-out and testing. Called the Rubis(S639), the boat is the latest in a planned fleet of six Suffren-class submarines.

These boats are intended to replace the French Navy’s existing Rubis-class SSNs, which have been in service since the 1980s. This replacement programme hopes to see all six new SSNs done and dusted by 2030.

Designed and built by the French shipbuilder Naval Group, the 326-foot (99-meter) long Rubisleft its construction hall on October 16, 2026, in Cherbourg. This means the submarine’s main structure is effectively now complete.

The boat now requires finishing touches like integrating and testing onboard systems, final work on propulsion, and installation of electrical and combat systems. Following this work, the Rubiswill begin sea trials, likely sometime in 2027, though no official date has been publicly announced.

5 out of 6 Suffrens

If the Rubispasses those trials, she will officially be ready for official acceptance by the French Navy, likely in late 2027. The sixth and final boat, the Casabianca (S640), will join its sisters sometime over the next few years.

The new Suffren-class (developed under the Barracudaprogramme) is a substantial upgrade over the Rubis-classand will enable the French Navy to maintain its attack submarine capability well into the middle of the century. Key features include its X-shaped rear rudder and control setup and pump-jet propulsion system.

The latter offers the class significant noise-reduction capabilities, increasing its underwater stealth capabilities.

SSNs like these are designed for conventional combat, but can also be used in intelligence gathering roles and fleet protection. Such submarines can be used to hunt and kill enemy submarines, and also attack surface ships unseen.

They also come with land strike capabilities and can be used for other specialist missions like covert operations. This can include missions like delivering combat divers into contested regions.

Its nuclear reactor gives it enormous endurance without needing to surface or snorkel to operate diesel engines. That said, things like food supplies, crew requirements, and maintenance are generally more limiting than fuel.

Futureproofing the navy

“It is with great pride and a deep sense of responsibility that we today transferred the Rubis, the fifth Suffren-class nuclear attack submarine, to its launch platform. This crucial milestone comes just 17 months after that of the nuclear attack submarine De Grasse, a symbol of our commitment to our customers,” said Pierre Éric Pommellet, Chairman and CEO of Naval Group.

“In an extremely challenging operational environment, manufacturers must rise to the occasion to deliver to sailors the ships they need to carry out their missions. This event is also an opportunity to recognize the integrated teamwork with the DGA, our partners, and the crew—the foundation of our collective success,” he added.

Looking ahead, the French Navy plans to upgrade the Suffren-class over its lifespan rather than allow them to become obsolete through its “Evol SNA.” This will allow them to modernize them as and when needed.

There are also plans afoot by the French defense procurement agency (DGA) called SNA3G, which are preliminary plans for an eventual replacement of the Suffren-classin the future. It is understood that this is not yet an official programme.