The following is the March 21, 2025, Congressional Research Service In Focus report, Navy Next-Generation Attack Submarine (SSN[X]) Program: Background and Issues for Congress.
From the report
Introduction
The Navy has been procuring Virginia-class nuclear powered attack submarines (SSNs) since FY1998. The Navy’s envisaged successor to the Virginia-class design is the Next-Generation Attack Submarine, or SSN(X). The Navy’s FY2024 budget submission envisaged procuring the first SSN(X) in FY2035. The Navy’s FY2025 budget submission defers the envisaged procurement of the first SSN(X) from FY2035 to FY2040 due, the Navy states, to limitations on the Navy’s total budget.
Submarines in the U.S. Navy
The U.S. Navy operates nuclear-powered ballistic missile submarines (SSBNs), nuclear-powered cruise missile and special operations forces (SOF) submarines (SSGNs), and nuclear-powered attack submarines (SSNs). The SSNs are general-purpose submarines that can perform a variety of peacetime and wartime missions.
Virginia-Class Program
When procured at a rate of two boats per year, Virginia-class SSNs (Figure 1) equipped with the Virginia Payload Module (VPM) have a current estimated procurement cost of more than $4.5 billion per boat. For additional information on Navy submarine programs, see CRS Report RL32418, Navy Virginia-Class Submarine Program and AUKUS Submarine (Pillar 1) Project: Background and Issues for Congress, by Ronald O’Rourke, and CRS Report R41129, Navy Columbia (SSBN-826) Class Ballistic Missile Submarine Program: Background and Issues for Congress, by Ronald O’Rourke.
Submarine Construction Industrial Base
U.S. Navy submarines are built by General Dynamics’ Electric Boat Division (GD/EB) of Groton, CT, and Quonset Point, RI, and Huntington Ingalls Industries’ Newport News Shipbuilding (HII/NNS), of Newport News, VA. These are the only two shipyards in the country capable of building nuclear-powered ships. GD/EB builds submarines only, while HII/NNS also builds nuclear-powered aircraft carriers. The submarine construction industrial base also includes hundreds of supplier firms, as well as laboratories and research facilities, in numerous states. Much of the material procured from supplier firms for building submarines comes from sole-source suppliers.
SSN(X) Program
Program Designation
In the designation SSN(X), the “X” means that the exact design of the boat has not yet been determined.
Procurement Schedule
The Navy’s FY2024 budget submission envisaged procuring the first SSN(X) in FY2035. The Navy’s FY2025 budget submission defers the envisaged procurement of the first SSN(X) from FY2035 to FY2040. The Navy’s FY2025 30-year (FY2035-FY2054) shipbuilding plan states: “The delay of SSN(X) construction start from the mid-2030s to the early 2040s presents a significant challenge to the submarine design industrial base associated with the extended gap between the Columbia class and SSN(X) design programs, which the Navy will manage.”
Design of the SSN(X)
The Navy states that the SSN(X) “will be designed to counter the growing threat posed by near peer adversary competition for undersea supremacy. It will provide greater speed, increased horizontal [i.e., torpedo-room] payload capacity, improved acoustic superiority and non-acoustic signatures, and higher operational availability. SSN(X) will conduct full spectrum undersea warfare and be able to coordinate with a larger contingent of off-hull vehicles, sensors, and friendly forces.” (Budget-justification book for FY2025 Research, Development, Test, and Evaluation, Navy account, Vol. 3 [Budget Activity 5], p. 1299.)
Navy officials have stated that the Navy wants the SSN(X) to incorporate the speed and payload of the Navy’s fast and heavily armed Seawolf (SSN-21) class SSN design, the acoustic quietness and sensors of the Virginia-class design, and the operational availability and service life of the Columbia-class design. These requirements will likely result in an SSN(X) design that is larger than the original Virginia-class design, which has a submerged displacement of about 7,800 tons, and possibly larger than the original SSN-21 design, which has a submerged displacement of 9,138 tons. Due to technological changes over the years for improved quieting and other purposes, the designs of U.S. Navy submarines with similar payloads have generally been growing in displacement from one generation to the next.
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