USS North Dakota rejoins US Navy battle force as new GAO report highlights worsening US submarine crisis.

On August 29, 2026, the U.S. Navy officially returned the Virginia-class attack submarine USS North Dakota (SSN 784) to operational service following a 40-month Extended Drydocking Selected Restricted Availability (EDSRA) at Portsmouth Naval Shipyard. The completion marks the shipyard’s first successful depot-level maintenance and modernization cycle performed on a Block III Virginia-class submarine. The availability integrated critical structural repairs, system overhauls, and upgraded bow array technologies to ensure readiness across the attack submarine fleet.

In parallel, a Government Accountability Office (GAO) report released in late August 2026 found that severe shipyard maintenance delays and backlogs caused the U.S. Navy to lose over 15,000 operational attack submarine days and incur $3.4 billion in idle sustainment costs between 2016 and 2025. The audit notes that attack submarine depot overhauls averaged 809 days between FY2021 and FY2025, and projects that 15 additional submarines will incur 14,000 inactive idle days costing $3.1 billion through FY2030. These maintenance backlogs effectively tie up roughly one-third of the 44-boat attack submarine inventory away from active deployments.

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The USS North Dakota's availability period had originally been planned for about 33 months and was valued at roughly $347 million, but the interval from arrival at Portsmouth to formal completion reached 40 months, seven months longer than planned. (Picture source: US Navy)

On August 29, 2026, the Virginia-class submarine USS North Dakota (SSN 784) returned to U.S. Navy service after completing its Extended Drydocking Selected Restricted Availability (EDSRA) at Portsmouth Naval Shipyard in Kittery, Maine, closing a maintenance and modernization period that had begun with the submarine's arrival on April 28, 2023. The availability had originally been planned for about 33 months and included roughly $347 million in system upgrades and associated work, but the interval from arrival at Portsmouth to formal completion reached 40 months, seven months longer than that planning benchmark. The USS North Dakota entered Portsmouth's Dry Dock No. 2 in September 2023 and remained there until February 26, 2026, meaning the dry-docking phase itself lasted close to 30 months.

The submarine then required almost another six months of pierside completion, integration, testing, and certification before departing Portsmouth for sea trials on August 20, 2026. It arrived at Pier 32N at Naval Submarine Base New London on August 27, two days before the availability formally ended. The submarine had entered the yard less than six months after returning on October 27, 2022, from a seven-month deployment that began on March 29 and included operations in the North Atlantic and European waters with port calls at Tromsø, Faslane, Toulon and Rota. The significance for the wider Virginia fleet is that Portsmouth has now completed its first full depot-level maintenance cycle on the configuration introduced by the USS North Dakota and shared by all eight Block III boats.

The USS North Dakota is the 11th Virginia-class attack submarine, the first Block III boat and the second U.S. Navy warship to carry the state name after the Delaware-class battleship USS North Dakota (BB-29). Its construction contract was awarded to General Dynamics Electric Boat on August 14, 2003. The keel was laid on May 11, 2012; the submarine was launched on September 15, 2013, christened on November 2, 2013, and delivered to the Navy on August 29, 2014. Delivery occurred two days ahead of the contractual date and more than $30 million below the target cost, although the program had encountered quality control and certification problems before commissioning. A May 2014 commissioning had to be postponed after defects in vendor-assembled components required an unscheduled dry-docking, while additional work was necessary to certify the new Block III bow configuration.

The USS North Dakota was ultimately commissioned on October 25, 2014. The submarine is 114.9 m long, with a beam of about 10.3 m, and a submerged displacement of about 7,800 tons. It is powered by one S9G pressurized-water reactor driving steam turbines and a single-shaft pump-jet propulsor, with speed exceeding 46 km/h and test depth greater than 240 m. The Virginia-class baseline crew is 132 personnel, including 15 officers and 117 enlisted sailors, although the USS North Dakota could reach 134. Its reactor core is intended to last for the submarine's full roughly 33-year service life without a mid-life refueling overhaul, which removes one major depot event compared with older U.S. nuclear submarines but does not eliminate long-duration maintenance periods for hull, propulsion, electrical, combat, and auxiliary systems. Block III changed about 40% of the Virginia-class bow, making the USS North Dakota structurally and functionally different from USS Virginia (SSN 774) through USS Minnesota (SSN 783).

The first ten Virginia-class submarines used 12 individual vertical-launch tubes (VLTs) for Tomahawk cruise missiles and a spherical main bow sonar array. The USS North Dakota replaced those 12 dedicated launchers with two large-diameter Virginia Payload Tubes (VPTs), each capable of carrying six Tomahawks, retaining a total capacity of 12 missiles while changing the launcher architecture from 12 small cells to two multipurpose tubes. The VPT design drew on the multiple all-up-round canister arrangement used aboard converted Ohio-class guided-missile submarines. The second major change was the replacement of the spherical sonar with the Large Aperture Bow (LAB) array. The LAB system uses a water-backed configuration rather than the older air-backed spherical arrangement and combines passive and medium-frequency active sonar functions.

These two modifications accounted for most of the roughly 40% bow redesign and altered hull structure, internal arrangements, sonar installation, and payload handling. The Block III purpose was mainly to lower acquisition and lifetime support costs while introducing larger-diameter payload spaces that could later support more flexible weapons and mission packages. Portsmouth's 2023-2026 work therefore provided the shipyard with direct maintenance experience on the first Virginia generation whose bow structure, launchers, and main sonar differ substantially from the original Block I and II design. The USS North Dakota has four 533 mm torpedo tubes for Mk 48 heavyweight torpedoes in addition to the two VPTs holding up to 12 vertically launched Tomahawks. Its acoustic suite includes the Large Aperture Bow sonar, a wide-aperture fiber-optic flank array using three flat panels on each side of the hull, high-frequency active sonar associated with the bow and sail, and tactical and long-range towed arrays.

Systems associated with the class include the TB-16 and TB-34 larger-diameter towed arrays and TB-29 or TB-33 thin-line arrays for longer-range passive detection. Two photonics masts replaced traditional optical periscopes. Those masts use digital color, high-resolution black-and-white, and infrared cameras, allowing visual and infrared imagery to be transmitted electronically into the control room rather than through a hull-penetrating optical tube. Removing the optical periscope requirement allowed the control room to move one deck lower, eliminating the need to position it directly below the sail. Virginia-class boats also use fly-by-wire ship-control systems intended to improve maneuvering in shallow or confined waters, incorporate a lock-in/lock-out chamber for divers, and can reconfigure the torpedo room to accommodate special-operations personnel and equipment.

The USS North Dakota's use in a six-week operational-testing period in the Mediterranean in 2015 that involved unmanned underwater vehicles was therefore consistent with a class increasingly designed to operate external sensors and unmanned systems in addition to torpedoes and cruise missiles. However, the duration of the USS North Dakota's Portsmouth availability is more important for force generation than the date on which the submarine left dry dock. A 33-year service life equals 396 months. The original 33-month maintenance plan would consume 8.3% of that nominal lifetime, while the actual 40-month interval from April 28, 2023, to August 29, 2026, consumed 10.1%. Put another way, more than one-tenth of a 33-year submarine life passed during a single depot availability. The planned $347 million work package equated to $10.5 million for each of the 33 scheduled months, although that ratio includes modernization and component replacement and is not a measure of normal operating cost.

The USS North Dakota's timeline also demonstrates why counting dry-dock days alone understates the readiness burden. The submarine left Dry Dock No. 2 on February 26, 2026, but did not depart for sea trials until August 20, a gap of 175 days. During those 175 days, the dry dock was available for other work, but the USS North Dakota itself was still not operationally available. For the U.S. Navy's fleet-level readiness, the relevant interval is the full period between induction and return to service, because a submarine undergoing pierside integration, certification, or post-maintenance testing contributes as little deployed presence as one physically sitting in a dry dock. With only 44 attack submarines in the FY2025 inventory, several additional months of post-docking work on each boat quickly translate into multiple submarine-years of unavailable capacity across the force.

Portsmouth itself illustrates why attack submarine maintenance cannot be measured simply by the number or length of dry docks. The yard dates to 1800, ended submarine construction after USS Sand Lance in 1969, and now concentrates on overhaul, repair, and modernization of nuclear-powered submarines. Naval Support Activity Maine covers more than 120 hectares across its main and associated facilities and supports roughly 8,000 civilian employees and 1,000 military personnel. The yard normally supports about four submarine crews in addition to Coast Guard units. Its three principal dry docks have markedly different dimensions. Dry Dock No. 1 is 132.7 m long, 31.7 m wide and 7.6 m deep. Dry Dock No. 2 is 209.2 m long, 39.3 m wide and 9.25 m deep. Dry Dock No. 3 is 148.1 m long, 21.6 m wide and 11.3 m deep. At 114.9 m, North Dakota occupied only 54.9% of the length of Dry Dock No. 2, leaving more than 94 m of unused longitudinal space, but that does not mean the dock could simultaneously process another SSN.

Nuclear maintenance depends on certified work boundaries, cranes, temporary services, nuclear-qualified trades, electrical and water systems, radiological controls, production shops, engineering support, component availability, testing teams, and specialized tooling. Portsmouth has also had other Virginia-class boats in its workload, including USS Washington (SSN 787) and USS New Mexico (SSN 779). The limiting factor is therefore not whether a 114.9-m hull physically fits inside a 209.2-m dock, but whether the complete industrial organization can move multiple nuclear submarines through disassembly, repair, reassembly, testing, and certification at the scheduled rate. The wider attack submarine fleet also shows why the USS North Dakota's return cannot be treated as an isolated maintenance event.

The U.S. Navy had 44 attack submarines in FY2025, yet maintenance backlogs and shipyard delays had already produced roughly 15,000 lost operational days, according to a new GAO report. Fifteen thousand days equal 41.1 submarine-years of lost availability, nearly the equivalent of removing the entire FY2025 SSN force from service for 11 months. Sustaining Virginia submarines and crews during those unavailable periods generated about $3.4 billion in costs, equivalent to roughly $226,700 for each lost operational day. Maintenance performance also deteriorated between consecutive five-year periods. Attack submarine depot delays totaled 3,040 days in FY2016-FY2020 and 3,454 days in FY2021-FY2025, an increase of 414 days, or 13.6%. Average depot duration increased from 744 days to 809 days, a rise of 65 days, or 8.7%.

An 809-day average equals 26.6 months, meaning a typical depot period now removes a submarine from normal availability for more than two years before additional schedule disruption is considered. Roughly one-third of the SSN force has at times been in maintenance or waiting for maintenance. Applied to a 44-boat inventory, one-third represents 14.7 submarines, leaving only 29.3 outside that maintenance population before accounting for training, certification, transit, crew workups, or other non-deployed status. That is significantly different from a headline inventory figure of 44. The cost of keeping submarines idle compounds the operational loss. A Los Angeles-class attack submarine can cost nearly $220,000 per inactive day and a Virginia-class submarine more than $237,000.

At the Virginia rate, 100 idle days cost more than $23.7 million, one year costs more than $86.5 million, and an 809-day period corresponds to more than $191 million if the daily sustainment figure were applied continuously. The problem is projected to continue. Fifteen attack submarines could enter inactive-idle status between FY2026 and FY2030, creating more than 14,000 additional inactive days. Fourteen thousand days equal 38.4 submarine-years. Expected operating and support costs therefore exceed $3.1 billion, corresponding to more than $221,000 per inactive day. Separate from those boats, submarines awaiting disposal generated about $722 million in costs between 2016 and 2025. The result is a three-part burden on the U.S. Navy: operational submarines are removed from fleet tasking while waiting for or undergoing maintenance, inactive boats continue consuming money and personnel, and decommissioned or decommissioning submarines still require resources before they can be fully disposed of.

Increasing the nominal submarine inventory, subsequently, does not solve that problem unless maintenance throughput increases at the same time. The USS Boise (SSN 764) provides the clearest example of how delay can eventually destroy the economic case for returning a submarine to service. The Los Angeles-class boat last deployed in 2015 and lost its dive certification in 2017. In 2024, the U.S. Navy awarded a $1.2 billion overhaul contract intended to restore the submarine. By April 2026, about $800 million had already been spent, but only about 22% of the work was complete. Finishing the overhaul was expected to require another $1.9 billion, increasing projected total expenditure to roughly $2.7 billion. At that point, the USS Boise was expected to have only about 20% of its planned service life remaining after completion. Therefore, the U.S. Navy terminated the overhaul plan on April 10, 2026, rather than commit the additional funding.

The case demonstrates why maintenance delay is not simply a scheduling issue. Each year spent waiting for work reduces the number of service years available after overhaul, while inflation, labor costs, emergent repairs, and equipment obsolescence can increase the cost of restoring the boat. Eventually, the cost per recovered operational year can become higher than the U.S. Navy is willing to accept, and the fleet loses the submarine permanently even though it remains part of the force structure problem that maintenance was originally supposed to solve. The construction side of the problem provides little margin to replace those losses. The U.S. Navy's force plan requires roughly two Virginia-class submarines per year, while sustaining U.S. requirements and planned AUKUS transfers raise the necessary production rate to about 2.33 annually. Actual sustained output has been closer to 1.0 to 1.2 submarines per year.

At 1.2 boats annually, the industrial base reaches only 60% of the U.S. Navy's two-per-year requirement and 51.5% of the 2.33-per-year U.S.-AUKUS requirement. The annual shortfall is 0.8 submarines against the U.S. Navy-only requirement and 1.13 against the combined requirement. Sustained over five years, production at 1.2 per year yields six submarines, compared with ten needed for the U.S. Navy alone and 11.65 for the combined requirement. The shortfall would therefore reach four submarines against the U.S. Navy target or 5.65 against the higher requirement before accounting for construction delays. The two Virginia-class submarines accepted in 2025 were each more than three years late, showing that nominal annual procurement plans do not translate directly into on-time fleet deliveries.

Virginia production also competes with the Columbia-class ballistic missile submarine program for nuclear-qualified welders, engineers, shipfitters, machining capacity, specialized suppliers, and production space. Moreover, the Columbia-class receives the priority because late delivery of those boats could affect both the replacement of the Ohio-class ballistic-missile submarine fleet and the continuity of the U.S. sea-based nuclear deterrent. The USS North Dakota's August 29 return therefore adds one attack submarine to the usable force at a time when the central SSN problem is the gap between inventory, construction output, and actual operational availability. A force of 44 attack submarines can fall effectively below 30 boats outside maintenance or maintenance queues when roughly one-third of the inventory is unavailable for those reasons.

The U.S. operational submarine force is therefore determined by four interacting rates: how quickly new Virginias are delivered, how many older Los Angeles-class boats retire, how long submarines remain in depot maintenance, and how many boats are waiting for maintenance that shipyards do not yet have capacity to begin. Portsmouth completing the first Block III depot cycle removes one submarine from that backlog and provides experience relevant to seven other boats of the same block, but it does not change the basic arithmetic. As long as construction remains near half the combined U.S.-AUKUS requirement and major maintenance periods routinely consume more than two years, the number of SSNs available for deployment will remain materially below the number carried in the U.S. Navy's inventory, a crucial point against Chinese and Russian naval forces.

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.

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