Naval Sea Systems Command awarded General Dynamics Electric Boat Corporation a not-to-exceed $2,305,530,000 undefinitized contract action modification on May 11 for long lead time material procurement and early manufacturing activities in support of Virginia-class Block VI submarine construction. The UCA, executed under existing contract N00024-24-C-2110, authorizes Electric Boat to begin purchasing nuclear propulsion components, high-strength steel, and specialized systems with lead times of three to five years before the final negotiated price is established. Work will be performed primarily in Sunnyvale, California, which accounts for 30 percent of the contract value; Groton, Connecticut; and 15 additional locations across the submarine industrial base. The ordering period runs through September 2035, spanning the anticipated construction timeline for the first Block VI vessels.
What an Undefinitized Contract Action Means
An undefinitized contract action is a contractual instrument that allows the government to authorize a contractor to begin work and incur costs before the final contract price, terms, and conditions have been negotiated. The Defense Federal Acquisition Regulation Supplement imposes strict limitations on UCAs: the contractor may not be reimbursed for more than 50 percent of the not-to-exceed ceiling before definitization, and definitization must occur within 180 days of the initial authorized work or before 50 percent of the work is complete, whichever comes first. The $2.3 billion not-to-exceed ceiling on this UCA represents the maximum the government will pay before the parties negotiate the final contract value. UCAs are used in submarine construction because nuclear propulsion components — reactor pressure vessels, steam generators, turbines, and associated piping — have lead times measured in years and cannot be ordered after the construction contract is definitized without creating gaps in the production schedule that would delay vessel delivery.
For the Virginia-class program, which has been struggling to reach its congressionally mandated two-submarines-per-year production rate, early ordering of long-lead components is essential to sustaining schedule momentum. The submarine industrial base has faced workforce and supplier capacity constraints since the COVID-19 pandemic disrupted skilled trades training pipelines, and Electric Boat and its supplier network have been working to rebuild capacity. The UCA mechanism allows NAVSEA to commit procurement funding for Block VI components even before the detailed design specifications for Block VI-specific improvements are fully locked down, preserving schedule flexibility while the program office finalizes requirements.
Block VI in the Virginia-Class Evolution
Virginia-class submarines have been built in successive design blocks since the lead vessel, USS Virginia, was delivered in 2004. Each block introduces improvements in systems, combat capability, and construction efficiency. Block V, currently in production at Electric Boat in Groton and HII's Newport News Shipbuilding, introduced the Virginia Payload Module — an 84-foot hull plug that adds four large-diameter payload tubes capable of carrying up to 28 Tomahawk cruise missiles or other large payloads, nearly tripling the submarine's vertical strike capacity. Block VI is expected to build on Block V's expanded payload capability with improvements to the combat management system, acoustic sensors, and potentially the propulsion plant, though the specific technical changes remain classified at the detailed level. The Navy's goal is to have the first Block VI vessel on contract and in early construction before the last Block V boats are completed, maintaining the industrial continuity that sustains the approximately 38,000 workers employed across the submarine construction supply chain.
Congressional interest in Virginia-class production rate has intensified as the Navy's force structure plans and the AUKUS agreement create overlapping demands on the submarine industrial base. The AUKUS partnership's commitment to provide Australia with nuclear-powered submarines — beginning with Virginia-class vessels in the early 2030s — adds a third demand signal on top of U.S. Navy new construction and life extension work at the public naval shipyards. Electric Boat has publicly committed to increasing its Groton workforce by several thousand workers over the next five years to meet these combined demands, and the Block VI UCA is a financial signal that the program office is committed to funding that expansion.
What It Means for Contractors
The $2.3 billion UCA establishes the financial baseline for Block VI long-lead procurement and creates immediate downstream demand across the submarine industrial base.
- Suppliers of nuclear propulsion components — reactor pressure vessels, steam generators, turbine sets, and associated valves and piping systems — should engage Electric Boat's Groton and Quonset Point supplier programs directly to understand the Block VI long-lead procurement schedule; these components have lead times that make early supplier qualification a hard requirement for participation.
- High-strength steel producers, particularly those supplying HY-80 and HY-100 steel plate to the submarine program, should expect Block VI procurement to stress existing capacity and should work with NAVSEA's submarine industrial base office on workforce and capital investment plans that align with the UCA schedule.
- The Sunnyvale, California work allocation — 30 percent of UCA value — reflects GD Mission Systems' role in developing and producing the combat management system and associated electronics; firms in the defense electronics and systems integration space should engage GD Mission Systems Sunnyvale on Block VI subcontracting opportunities.
- NAVSEA's submarine program office periodically holds industry days and publishes industrial base strategy documents that identify supply chain gaps; firms that have not engaged the submarine program recently should review the publicly available Industrial Base Assessment to identify where Block VI creates new entry points.
AUKUS and the Compounding Demand Signal
The Block VI UCA arrives as the submarine industrial base faces a demand signal that is genuinely unprecedented in the post-Cold War era. The AUKUS trilateral security partnership committed the United States, United Kingdom, and Australia to delivering nuclear-powered attack submarines to the Royal Australian Navy beginning in the early 2030s. The initial pathway involves Australia purchasing three to five Virginia-class submarines directly from the U.S. Navy before a new trilaterally designed SSN-AUKUS class enters service. That commitment creates a third demand stream alongside U.S. Navy new construction and life extension work at the four public naval shipyards. Electric Boat's total workforce expansion commitment — multiple thousands of new workers at Groton and Quonset Point over the next five years — is sized to address all three demand streams simultaneously. Suppliers that serve the Virginia-class program today should assess whether their capacity commitments are adequate to support a production rate higher than any seen in the submarine program since the late Cold War era.