U.S. Navy to commission eighth Block IV Virginia-class submarine USS Idaho in April 2026.

The U.S. Navy will commission the 8th Virginia-class Block IV submarine USS Idaho (SSN-799) on April 25, 2026, at Naval Submarine Base New London in Groton, Connecticut.

On February 5, 2026, the USS Idaho Commissioning Committee confirmed that the U.S. Navy will commission the Virginia-class Block IV submarine USS Idaho (SSN-799) on April 25, 2026, at its future home port, the Naval Submarine Base New London in Groton, Connecticut. Launched on August 6, 2024, the USS Idaho submarine was delivered to the U.S. Navy on December 15, 2025, following completion of alpha sea trials and post-delivery testing. Commissioning will formally place the SSN-799 into active fleet service, as the 26th Virginia-class nuclear-powered fast-attack submarine built for the U.S. Navy and the eighth Block IV unit.
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The SSN 799 submarine is the fifth U.S. Navy ship to bear the name Idaho, following earlier vessels such as the battleship BB-42, commissioned in 1919, which served in the battles of Iwo Jima and Okinawa and was present during the surrender of Japan on September 2, 1945. (Picture source: U.S. Navy)

The commissioning of the Block IV Virginia-class submarine USS Idaho (SSN-799) is set for April 25, 2026, at 11 a.m. Eastern Daylight Time at its future home port, the Naval Submarine Base New London in Groton, Connecticut. The ceremony will formally place the submarine into active service within the U.S. Navy fleet following its delivery on December 15, 2025, and completion of post-delivery trials and preparations. The USS Idaho completed alpha sea trials in November 2025 before acceptance and transfer to Navy control. Until commissioning, the vessel is referred to as the Pre-Commissioning Unit USS Idaho. The April 25 ceremony marks the final milestone in a multi-year build, test, and delivery sequence for this Virginia-class Block IV nuclear-powered fast-attack submarine. 

The USS Idaho (SSN-799) was authorized under a contract awarded on April 28, 2014, as part of the multi-year Virginia-class procurement program, with the name Idaho officially announced on August 23, 2015. The keel was then laid on August 24, 2020, at General Dynamics Electric Boat’s Quonset Point facility in North Kingstown, Rhode Island, marking the formal start of construction. The submarine was christened on March 16, 2024, in Groton, Connecticut, with Teresa Stackley serving as sponsor, and it was launched on August 6, 2024, using a float-off method. Subsequent milestones for the USS Idaho included the first reactor startup on July 4, 2025, crew moving aboard on August 14, 2025, and a galley opening on August 21, 2025.

Alpha Sea Trials were completed in November 2025, and delivery to the U.S. Navy took place on December 15, 2025, positioning the boat for commissioning on April 25, 2026. The USS Idaho (SSN-799) is also the 26th Virginia-class nuclear-powered attack submarine constructed under the long-standing teaming arrangement between General Dynamics Electric Boat and HII Newport News Shipbuilding, and it is the 14th Virginia-class submarine delivered by Electric Boat. It is also the eighth of ten Block IV submarines, a configuration intended to reduce maintenance periods and increase operational availability compared with earlier blocks while retaining the Virginia-class’s multi-mission profile.

The Virginia-class submarine program began in the early 1990s under the codename Centurion, later renamed New SSN, as the U.S. Navy sought a less costly alternative to the Seawolf-class following the end of the Cold War, while also replacing Los Angeles-class attack submarines. The Virginia-class is designed to maintain several U.S. Navy capabilities for open-ocean and littoral operations, including anti-submarine warfare, strike missions with Tomahawk cruise missiles, intelligence collection, and special operations support as those earlier classes retire. Reported unit costs have been about $2.8 billion per submarine for earlier boats and about $4.3 billion for boats equipped with the Virginia Payload Module. 

The first boat, the USS Virginia (SSN-774), was laid down in 1999, launched in 2003, and commissioned on October 3, 2004, establishing the baseline design that would evolve through Blocks I to V. The class is built through a teaming arrangement between General Dynamics Electric Boat and Newport News Shipbuilding, with production structured in multi-year contracts including a $14 billion agreement in December 2008 for eight submarines, a $17.6 billion contract in April 2014 for ten submarines, and a $22 billion contract in December 2019 for nine Block V submarines to stabilize output and reduce unit costs. Block I and II Virginia-class submarines were equipped with 12 individual vertical launch system (VLS) tubes, while Block III and IV boats replaced these with two Virginia Payload Tubes capable of launching six Tomahawk missiles each.

Beginning with Block V, the Virginia Payload Module adds four large-diameter payload tubes capable of carrying seven Tomahawk missiles each, increasing total strike capacity to 40 missiles. The USS Idaho has a submerged displacement of about 7,800 tonnes, a length of 115 meters, a beam of 10.4 meters, and a draft of 9.8 meters, consistent with Block I through Block IV Virginia-class dimensions. Propulsion is provided by an S9G nuclear reactor supplemented by an auxiliary diesel generator, enabling sustained submerged operations for up to three months and speeds exceeding 25 knots. Test depth is stated as greater than 244 meters. The standard crew complement includes roughly 15 officers and 120 enlisted personnel, while broader Virginia-class data lists a complement of about 135 to 145 personnel depending on configuration.

The reactor plant is designed to operate for the life of the submarine without refueling, supporting an expected service life exceeding three decades. Armament for Block III and Block IV boats, such as the USS Idaho, includes two Virginia Payload Tubes, each capable of launching six Tomahawk cruise missiles, for a total of 12 vertically launched missiles. The submarine also carries four 533 mm torpedo tubes for Mk-48 heavyweight torpedoes and can launch additional weapons, including submarine-launched cruise missiles from the torpedo tubes. Earlier Block I and Block II submarines were equipped with 12 individual vertical launch system tubes, while later Block V boats incorporate the Virginia Payload Module with four additional large-diameter payload tubes capable of carrying seven Tomahawk missiles each, increasing total vertical launch capacity to 40 missiles.

The AN/BYG-1 combat system integrates sensors, navigation, and weapon control, and sonar systems include bow-mounted active and passive arrays, wide-aperture flank arrays, high-frequency arrays, and towed array systems. The class incorporates photonic masts instead of traditional periscopes, using high-resolution cameras, infrared sensors, and laser rangefinders mounted on non-hull-penetrating structures, which allows the control room to be positioned away from the sail. Pump-jet propulsion replaces a traditional propeller to reduce acoustic signature and cavitation risk. Modular construction and open-architecture systems are intended to support upgrades over the submarine’s service life.

Within the broader attack submarine force, the U.S. Navy operates Virginia-class, Seawolf-class, and Los Angeles-class submarines, with the Virginia class becoming the most numerous active submarine class after the decommissioning of USS Helena SSN-725 in July 2025. The Virginia class is planned to remain in service into the 2060s, with later boats expected to operate into the 2070s. Much of the advanced acoustic stealth technology for the USS Idaho is linked to work conducted at the U.S. Navy’s Acoustic Research Detachment in Bayview, Idaho, located on Lake Pend Oreille, which is home to the largest unmanned submarine in the world certified by the Guinness World Records, the LSV-2 Cutthroat.

Modern nuclear technology developed at the Idaho National Laboratory enables the submarine to conduct its mission for 35 years before refueling. The engine room will be named after former Idaho Governor and U.S. Senator Dirk Kempthorne, reflecting his role as chairman of the USS Idaho Commissioning Advisory Board and his advocacy for the project. USS Idaho is the fifth U.S. Navy ship to bear the name, following earlier vessels including a wooden-hulled storeship commissioned in 1866 and battleship BB-42, commissioned in 1919, which served in the battles of Iwo Jima and Okinawa and was present in Tokyo Bay during the signing of the formal surrender of Japan on September 2, 1945.

Written by Jérôme Brahy

Jérôme Brahy is a defense analyst and documentalist at Army Recognition. He specializes in naval modernization, aviation, drones, armored vehicles, and artillery, with a focus on strategic developments in the United States, China, Ukraine, Russia, Türkiye, and Belgium. His analyses go beyond the facts, providing context, identifying key actors, and explaining why defense news matters on a global scale.