The following is the Aug. 4, 2023, Congressional Research In Focus report, Navy Next-Generation Attack Submarine (SSN[X]) Program: Background and Issues for Congress.
From the report
The Navy wants to begin procuring a new class of nuclear-powered attack submarine (SSN), called the Next-Generation Attack Submarine or SSN(X), in the mid-2030s. The SSN(X) would be the successor to the Virginia-class SSN design, which the Navy has been procuring since FY1998. The Navy’s proposed FY2024 budget requests $544.7 million in research and development funding for the SSN(X) program.
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.
As mentioned above, the Navy has been procuring Virginia-class SSNs since FY1998. Since FY2011, the Navy has been procuring them at a rate of two boats per year. When procured at a rate of two boats per year, Virginia-class SSNs equipped with the Virginia Payload Module (VPM) have a current estimated procurement cost of about $4.3 billion per boat. (Most Virginia-class boats procured in FY2019 and subsequent years are to be built with the VPM, an additional mid-body section equipped with four large-diameter, vertical launch tubes.) For additional information on Navy submarine programs, see CRS Report RL32418, Navy Virginia (SSN-774) Class Attack Submarine Procurement: 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.
In the designation SSN(X), the “X” means that the exact design of the boat has not yet been determined.
The Navy wants to shift from procuring Virginia-class boats to procuring SSN(X)s in the mid-2030s.