France advances strategic naval capabilities with launch of fourth Suffren-class submarine.

On May 27, 2025, the French Directorate General of Armaments (DGA) reported the transfer of the nuclear-powered attack submarine De Grasse (S638) from Naval Group’s construction hall in Cherbourg to the floating launch platform located in the Cachin basin. This movement marks a significant procedural phase in the Barracuda program, which aims to replace the Rubis-class submarines with six Suffren-class units. Following this step, the submarine will undergo dockside completion work and initial tests before a first launch scheduled in 2026, after which a full sea trial campaign will begin. This unit is the fourth submarine of the class and is part of the sequence of deliveries expected to be completed by 2030 under the current Military Planning Law (2024–2030).
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Unlike the Rubis class, the Suffren class introduces the ability to launch MdCN cruise missiles against targets at distances greater than 1,000 kilometers. (Picture source: X/DGA)

France maintains one of the most capable and autonomous submarine forces in Europe. This dual-component submarine force, composed of four Triomphant-class ballistic missile submarines and six planned Suffren-class nuclear attack submarines. The SSBNs carry France’s strategic nuclear deterrent, while the SSNs are tasked with missions including protection of strategic assets, underwater intelligence collection, escort of carrier and amphibious groups, anti-submarine warfare, and strikes against land targets using naval cruise missiles. Unlike the Rubis class, the Suffren class introduces the ability to launch MdCN cruise missiles against targets at distances greater than 1,000 kilometers. The submarines can also deploy Special Forces using a dedicated dry deck shelter and underwater vehicles. The Suffren-class thus supports a broader range of missions, from deterrence support to participation in multinational operations in the Mediterranean, North Atlantic, and Indo-Pacific regions.

The De Grasse submarine measures 99.5 meters in length, 8.8 meters in beam, with a submerged displacement of 5,300 tons. It uses a hybrid propulsion system comprising a 150 MW K15 pressurized water reactor, two 10 MW turbo-generators, and two SEMT Pielstick 480 kW diesel generators. Propulsion is delivered via a pump-jet that enhances acoustic discretion. The platform allows speeds exceeding 25 knots submerged and up to 14 knots surfaced. The hull is constructed with high-yield 80HLES steel and is rated for depths beyond 350 meters. Onboard systems enable submerged operations for up to 70 days, limited only by food stocks. Crew size is 63, and the design allows the embarkation of 15 additional commandos. The submarine’s interior includes accommodations for mixed-gender crews and is built to sustain continuous operations for more than 270 days per year using a dual-crew rotation model.

The De Grasse carries a diverse suite of weapons and sensors. It is equipped with four 533 mm torpedo tubes and 20 storage racks. The submarine can launch F21 Artemis torpedoes with a range of 50 kilometers, Exocet SM39 Mod 2 anti-ship missiles, MdCN cruise missiles, FG29 naval mines, and the D-19 autonomous underwater vehicle. Sensors include the Thales UMS-3000 flank and bow sonar arrays, ETBF DSUV 62C towed sonar, SEACLEAR mine and obstacle avoidance sonar, VELOX-M8 intercept sonar, and NUSS-2F Mk2 navigation echo sounder. The SYCOBS combat management system processes sensor data for targeting. Communications systems include the Thales PARTNER suite, DIVESAT mast for Syracuse satellite access, and tactical links including Link 11, 16, and 22. The vessel also features two optronic masts and a NEMESIS electronic countermeasure system with CANTO-S decoys and automated evasion algorithms. For special operations, the submarine includes a removable dry deck shelter capable of deploying the PSM3G swimmer delivery vehicle.

The rollout of De Grasse increases the number of operational Suffren-class submarines in France’s naval force and supports the transition from the Rubis class. This addition improves operational availability and reduces dependency on the existing fleet. With a total of six submarines planned, the French Navy aims to maintain a high-tempo deployment capability in multiple theaters of operation while supporting strategic autonomy. The inclusion of land-attack and special operations capabilities enables the Suffren class to participate in joint and national missions across a range of scenarios. The submarine fleet plays a central role in protecting French maritime interests, ensuring freedom of navigation, and maintaining a continuous underwater presence for intelligence and deterrence. The completion of De Grasse’s launch phase ensures that the Navy remains on schedule for the full implementation of the Barracuda program by 2030, aligned with current budgetary and defense planning frameworks.