The U.S. Navy appears to be leaning toward developing a new, advanced fast attack submarine that focuses more on hunting maritime threats above and below the waves than on stand-off strikes against targets ashore. The decision would reflect growing concerns about Russian and Chinese submarine activity, but could come at a steep price of more than $5 billion per sub. USNI News was one of the first to spot that the Congressional Budget Office explored the Navy’s shifting priorities in its analysis of the service’s latest shipbuilding plan for the 2019 through 2048 Fiscal Years, which it released on Oct. 18, 2018. Purchases of the Virginia-class attack submarine are supposed to end in 2033, after which the Navy expects to begin buying new boats to succeed that design at a rate of two every year through 2048. This would result in a fleet of 30 of the new subs, presently referred to simply as SSN(X).

“Specifically, the Navy indicates that the next-generation attack submarine should be faster, stealthier, and able to carry more torpedoes than the Virginia class – similar to the Seawolf class submarine,” CBO’s analysts wrote in their review. “CBO therefore assumed that the SSN(X) would be a Seawolf-sized SSN, which displaces about 9,100 tons when submerged, and would have an all-new design in keeping with the Navy’s description of it as a ‘fast, lethal, next-generation attack submarine.’”

USN The Seawolf-class submarine USS Connecticut.

In 1983, General Dynamics Electric Boat began designing the Seawolf-class for the Navy as a successor to the Los Angeles-class attack submarine. Significantly more advanced, the Seawolfs were also much costlier to build. Their unit cost of more than $3 billion – closer to $5 billion in 2018 dollars – made them the most expensive attack submarine ever designed and the second most expensive submarine of any kind, ever, at the time. With the apparent need for the boats gone after the end of the Cold War, the United States canceled the program in 1995 and ultimately purchased just three of the 29 examples it had originally planned to buy. The Seawolf-class submarines have since been assigned a number of secretive special duties that make good use of their enhanced performance and deep-diving capabilities, which make them particularly well suited to operations under the ice in the increasingly strategic Arctic region. The last example, the USS Jimmy Carter, also received significant modifications to operate as a spy submarine.

CBO A graph showing the planned shift in the Navy's attack submarine fleets between 2018 and 2048, which also shows the older Los Angeles-class boats out of service by around 2033 and the Seawolfs heading into retirement by 2038.

The Navy subsequently moved on to the Virginia-class, a smaller, less expensive, multi-mission design with 12 vertical launch system cells for firing Tomahawk land-attack cruise missiles and features allowing them to more readily work in littoral environments to collect intelligence and insert and extract special operations forces. Starting with the Block V Virginias, the submarines will also gain the Virginia Payload Module (VPM), which adds four large diameter tubes for additional Tomahawks, other long-range weapons, or unmanned undersea vehicles. The Navy had originally described SSN(X) as an evolution of the late model Virginia-class boats with the VPM. Now, the plan appears to be to return to a design better suited for conducting missions against enemy surface ships and submarines that has the capacity to carry more torpedoes, according to CBO.

USN A 2013 briefing slide explaining the VPM modifications to the Block V Virginia-class submarines.