This report provides background information and issues for Congress on the Virginia-class nuclear-powered attack submarine (SSN) program. The Navy's proposed FY2020 budget requests $9,925.5 million (i.e., about $9.9 billion) in procurement and advance procurement (AP) funding for the program. Decisions that Congress makes on procurement of Virginia-class boats could substantially affect U.S. Navy capabilities and funding requirements, and the U.S. shipbuilding industrial base. The Navy's Columbia (SSBN-826) class ballistic missile submarine program is discussed in another CRS report—CRS Report R41129, Navy Columbia (SSBN-826) Class Ballistic Missile Submarine Program: Background and Issues for Congress , by Ronald O'Rourke. For an overview of the strategic and budgetary context in which the Virginia-class program and other Navy shipbuilding programs may be considered, see CRS Report RL32665, Navy Force Structure and Shipbuilding Plans: Background and Issues for Congress , by Ronald O'Rourke. The U.S. Navy operates three types of submarines—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 (when appropriately equipped and armed) perform a variety of peacetime and wartime missions, including the following: covert intelligence, surveillance, and reconnaissance (ISR), much of it done for national-level (as opposed to purely Navy) purposes; covert insertion and recovery of SOF (on a smaller scale than possible with the SSGNs); covert strikes against land targets with the Tomahawk cruise missiles (again on a smaller scale than possible with the SSGNs); covert offensive and defensive mine warfare; anti-submarine warfare (ASW); and anti-surface ship warfare. During the Cold War, ASW against Soviet submarines was the primary stated mission of U.S. SSNs, although covert ISR and covert SOF insertion/recovery operations were reportedly important on a day-to-day basis as well. In the post-Cold War era, although anti-submarine warfare remained a mission, the SSN force focused more on performing the other missions noted on the list above. Due to the shift in the strategic environment in recent years from the post-Cold War era to a new situation featuring renewed great power competition, ASW against Russian and Chinese submarines has once again become a more prominent mission for U.S. Navy SSNs. The Navy's force-level goal, released in December 2016, is to achieve and maintain a 355-ship fleet, including 66 SSNs. For a review of SSN force-level goals since the Reagan Administration, see Appendix A . The SSN force included more than 90 boats during most of the 1980s, when plans called for achieving a 600-ship Navy including 100 SSNs. The number of SSNs peaked at 98 boats at the end of FY1987 and declined after that in a manner that roughly paralleled the decline in the total size of the Navy over the same time period. The 51 SSNs in service at the end of FY2018 included the following: 31 Los Angeles (SSN-688) class boats; 3 Seawolf (SSN-21) class boats; and 17 Virginia (SSN-774) class boats. A total of 62 Los Angeles-class submarines, commonly called 688s, were procured between FY1970 and FY1990 and entered service between 1976 and 1996. They are equipped with four 21-inch diameter torpedo tubes and can carry a total of 26 torpedoes or Tomahawk cruise missiles in their torpedo tubes and internal magazines. The final 31 boats in the class (SSN-719 and higher) were built with an additional 12 vertical launch system (VLS) tubes in their bows for carrying and launching another 12 Tomahawk cruise missiles. The final 23 boats in the class (SSN-751 and higher) incorporate further improvements and are referred to as Improved Los Angeles class boats or 688Is. As of the end of FY2018, 31 of the 62 boats in the class had been retired. The Seawolf class was originally intended to include about 30 boats, but Seawolf-class procurement was stopped after three boats as a result of the end of the Cold War and associated changes in military requirements and defense spending levels. The three Seawolf-class submarines are the Seawolf (SSN-21), the Connecticut (SSN-22), and the Jimmy Carter (SSN-23). SSN-21 and SSN-22 were procured in FY1989 and FY1991 and entered service in 1997 and 1998, respectively. SSN-23 was originally procured in FY1992. Its procurement was suspended in 1992 and then reinstated in FY1996. It entered service in 2005. Seawolf-class submarines are larger than Los Angeles-class boats or previous U.S. Navy SSNs. They are equipped with eight 30-inch-diameter torpedo tubes and can carry a total of 50 torpedoes or cruise missiles. SSN-23 was built to a lengthened configuration compared to the other two ships in the class. The Virginia-class attack submarine (see Figure 1 ) was designed to be less expensive and better optimized for post-Cold War submarine missions than the Seawolf-class design. The Virginia-class design is slightly larger than the Los Angeles-class design, but incorporates newer technologies. Virginia-class boats procured in recent years cost roughly $2.8 billion each to procure, but Virginia-class boats to be procured in coming years will be built to a lengthened configuration that includes the Virginia Payload Module (see discussion below) and have an estimated unit procurement cost of roughly $3.2 billion. The first Virginia-class boat entered service in October 2004. Table 1 shows annual numbers of Virginia-class boats procured from FY1998 (the lead boat) through FY2019, the number requested for procurement in FY2020, and the numbers projected for procurement in FY2021-FY2024 under the FY2020-FY2024 Future Years Defense Plan (FYDP). Navy plans previously called for procuring two Virginia-class boats in FY2020. The third boat requested for FY2020 was added to the budget request as part of the FY2020 budget-planning cycle. The Navy states that since this third boat has not received any prior-year advance procurement (AP) funding, it would execute (i.e., be constructed) on a schedule similar to that of a boat procured in FY2023. The Virginia-class submarines shown in Table 1 for FY2019-FY2023, which are referred to as the Block V boats, are being procured under a multiyear procurement (MYP) contract covering those years. This is the fourth consecutive MYP contract used by the Virginia-class program—three earlier MYP contracts were used to procure the 10 Virginia-class boats shown in the table for the period FY2014-FY2018 (the Block IV boats), the 8 Virginia-class boats shown in the table for the period FY2009-FY2013 (the Block III boats), and the 5 Virginia-class boats shown in the table for the period FY2004-FY2008 (the Block II boats). The four boats shown in the table for the period FY1998-FY2002 (the Block I boats) were procured under a block buy contract, which is an arrangement somewhat similar to an MYP contract. The boat procured in FY2003 fell between the FY1998-FY2002 block buy contract and the FY2004-FY2008 MYP contract, and was contracted for separately. Virginia-class boats are built jointly 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. The arrangement for jointly building Virginia-class boats was proposed to Congress by GD/EB, HII/NNS, and the Navy, and agreed to by Congress in 1997, as part of Congress's action on the Navy's budget for FY1998, the year that the first Virginia-class boat was procured. A primary aim of the arrangement is to minimize the cost of building Virginia-class boats at a relatively low annual rate in two shipyards (rather than entirely in a single shipyard) while preserving key submarine-construction skills at both shipyards. Under the arrangement, GD/EB builds certain parts of each boat, HII/NNS builds certain other parts of each boat, and the yards have taken turns building the reactor compartments and performing final assembly of the boats. The arrangement has resulted in a roughly 50-50 division of Virginia-class profits between the two yards and preserves both yards' ability to build submarine reactor compartments (a key capability for a submarine-construction yard) and perform submarine final-assembly work. Under a plan it calls the Submarine Unified Build Strategy (SUBS), the Navy plans to build Columbia-class ballistic missile submarines jointly at GD/EB and HII/NNS, with most of the work going to GD/EB. As part of this plan, the Navy plans to adjust the division of work on the Virginia-class attack submarine program so that HII/NNS would receive a larger share of the work for that program than it has received in the past. The Navy states that it achieved a goal of reducing the procurement cost of Virginia-class submarines so that two boats could be procured in FY2012 for a combined cost of $4.0 billion in constant FY2005 dollars—a goal referred to as "2 for 4 in 12." Achieving this goal involved removing about $400 million (in constant FY2005 dollars) from the cost of each submarine. (The Navy calculated that the unit target cost of $2.0 billion in constant FY2005 dollars for each submarine translated into about $2.6 billion for a boat procured in FY2012.) As noted in CRS testimony in 2014, the Virginia (SSN-774) class attack program has been cited as an example of a successful acquisition program. The program received a David Packard Excellence in Acquisition Award from the Department of Defense (DOD) in 2008. Although the program experienced cost growth in its early years that was due in part to annual procurement rates that were lower than initially envisaged and challenges in restarting submarine production at Newport News Shipbuilding, the lead ship in the program was delivered within four months of the target date that had been established about a decade earlier, and until recently, ships had been delivered largely on cost and ahead of schedule. In March and April 2019, it was reported that GD/EB, HII/NNS, and their supplier firms were experiencing challenges in meeting scheduled delivery times as the Virginia-class program transitions over time from production of two "regular" Virginia-class boats per year to two VPM-equipped boats per year. As a result of these challenges, it was reported, the program has experienced months-long delays in efforts to build boats relative to their targeted delivery dates. The Navy plans to build the second of the two boats procured in FY2019, the second and third boats requested for procurement in FY2020, the second of the two boats planned for procurement in FY2021, and all subsequent Virginia-class boats with the Virginia Payload Module (VPM), an additional, 84-foot-long, mid-body section equipped with four large-diameter, vertical launch tubes for storing and launching additional Tomahawk missiles or other payloads. The VPM's vertical launch tubes are to be used to store and fire additional Tomahawk cruise missiles or other payloads, such as large-diameter unmanned underwater vehicles (UUVs). The four additional launch tubes in the VPM could carry a total of 28 additional Tomahawk cruise missiles (7 per tube), which would increase the total number of torpedo-sized weapons (such as Tomahawks) carried by the Virginia class design from about 37 to about 65—an increase of about 76%. Building Virginia-class boats with the VPM is intended to compensate for a sharp loss in submarine force weapon-carrying capacity that will occur with the retirement in FY2026-FY2028 of the Navy's four Ohio-class cruise missile/special operations forces support submarines (SSGNs). Each SSGN is equipped with 24 large-diameter vertical launch tubes, of which 22 can be used to carry up to 7 Tomahawks each, for a maximum of 154 vertically launched Tomahawks per boat, or 616 vertically launched Tomahawks for the four boats. Twenty-two Virginia-class boats built with VPMs could carry 616 Tomahawks in their VPMs. The Navy's FY2020 budget submission shows that Virginia-class boats with and without the VPM have estimated recurring unit procurement costs of roughly $3.2 billion and $2.8 billion, respectively. The joint explanatory statement for the FY2014 DOD Appropriations Act (Division C of H.R. 3547 / P.L. 113-76 of January 17, 2014) required the Navy to submit biannual reports to the congressional defense committees describing the actions the Navy is taking to minimize costs for the VPM. In addition to the VPM, the Navy is introducing acoustic and other improvements to the Virginia-class design that are intended to help maintain the design's superiority over Russian and Chinese submarines. The Navy estimates the combined procurement cost of the three Virginia-class boats requested for procurement in FY2020 at $9.274.4 (i.e., about $9.3 billion). The boats have received $1,756.9 million in prior-year "regular" advance procurement (AP) funding and $361.6 million in additional Economic Order Quantity (EOQ) AP funding for components of boats being procured under the FY2019-FY2023 MYP contract. The Navy's proposed FY2020 budget requests the remaining $7,155.9 million in procurement funding needed to complete the boats' estimated combined procurement cost, as well as $1,887.6 million in "regular" AP funding for Virginia-class boats to be procured in future fiscal years and $882.0 million in additional EOQ AP funding for components of boats to be procured under the FY2019-FY2023 MYP contract, bringing the total amount of procurement and AP funding requested for the program in FY2020 to $9,925.5 million (i.e., about $9.9 billion), excluding outfitting and post-delivery costs. U.S. Navy submarines are built by GD/EB and HII/NNS. 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 and is capable of building other types of surface ships. In addition to GD/EB and HII/NNS, the submarine construction industrial base includes hundreds of supplier firms, as well as laboratories and research facilities, in numerous states. Much of the total material procured from supplier firms for the construction of submarines comes from sole-source suppliers. For nuclear-propulsion component suppliers, an additional source of stabilizing work is the Navy's nuclear-powered aircraft carrier construction program. In terms of work provided to these firms, a carrier nuclear propulsion plant is roughly equivalent to five submarine propulsion plants. Much of the design and engineering portion of the submarine construction industrial base is resident at GD/EB; smaller portions are resident at HII/NNS and some of the component makers. Table 2 shows the Navy's projection of the number of SSNs over time if the Navy's FY2020 30-year shipbuilding plan were fully implemented. As can be seen in the table, the FY2020 30-year shipbuilding plan would achieve the Navy's 66-boat SSN force-level goal by FY2048. As also shown in the table, the number of SSNs is projected to experience (relative to a previous Navy SSN force-level goal of 48 boats) a valley or trough from the mid-2020s through the early 2030s, reaching a minimum of 42 boats (i.e., 24 boats, or about 36%, less than the current 66-boat force-level goal) in FY2027-FY2028. This projected valley is a consequence of having procured a relatively small number of SSNs during the 1990s, in the early years of the post-Cold War era. Some observers are concerned that this projected valley in SSN force levels could lead to a period of heightened operational strain for the SSN force, and perhaps also a period of weakened conventional deterrence against potential adversaries such as China. The projected SSN valley was first identified by CRS in 1995 and has been discussed in CRS reports and testimony every year since then. As one measure for mitigating this valley, the Navy's FY2020 budget submission proposes to refuel and extend the service life of two older Los Angeles (SSN-688) class submarines. The Navy states that this could be followed by refuelings and service life extensions for up to five more Los Angeles-class SSNs that would be funded in fiscal years beyond the FY2020-FY2024 Future Year Defense Plan (FYDP). In recent years, a number of the Navy's SSNs have had their deployments delayed due to maintenance backlogs at the Navy's four government-operated shipyards, which are the primary facilities for conducting depot-level maintenance work on Navy SSNs. Delays in deploying SSNs can put added operational pressure on other SSNs that are available for deployment. A November 2018 Government Accountability Office (GAO) report on the issue stated: The Navy has been unable to begin or complete the vast majority of its attack submarine maintenance periods on time resulting in significant maintenance delays and operating and support cost expenditures. GAO's analysis of Navy maintenance data shows that between fiscal year 2008 and 2018, attack submarines have incurred 10,363 days of idle time and maintenance delays as a result of delays in getting into and out of the shipyards. For example, the Navy originally scheduled the USS Boise to enter a shipyard for an extended maintenance period in 2013 but, due to heavy shipyard workload, the Navy delayed the start of the maintenance period. In June 2016, the USS Boise could no longer conduct normal operations and the boat has remained idle, pierside for over two years since then waiting to enter a shipyard…. GAO estimated that since fiscal year 2008 the Navy has spent more than $1.5 billion in fiscal year 2018 constant dollars to support attack submarines that provide no operational capability—those sitting idle while waiting to enter the shipyards, and those delayed in completing their maintenance at the shipyards. The Navy has started to address challenges related to workforce shortages and facilities needs at the public shipyards. However, it has not effectively allocated maintenance periods among public shipyards and private shipyards that may also be available to help minimize attack submarine idle time. GAO's analysis found that while the public shipyards have operated above capacity for the past several years, attack submarine maintenance delays are getting longer and idle time is increasing. The Navy may have options to mitigate this idle time and maintenance delays by leveraging private shipyard capacity for repair work. But the Navy has not completed a comprehensive business case analysis as recommended by Department of Defense guidelines to inform maintenance workload allocation across public and private shipyards. Navy leadership has acknowledged that they need to be more proactive in leveraging potential private shipyard repair capacity. Without addressing this challenge, the Navy risks continued expenditure of operating and support funding to crew, maintain, and support attack submarines that provide no operational capability because they are delayed in getting into and out of maintenance. The House Appropriations Committee, in its report ( H.Rept. 115-769 of June 20, 2018) on the FY2019 DOD Appropriations Act ( H.R. 6157 ) stated: SUBMARINE MAINTENANCE SHORTFALLS The Committee recognizes that the nuclear-capable public naval shipyards are backlogged with submarine maintenance work, while private nuclear-capable shipyards have underutilized capacity. The Los Angeles (SSN–688) class submarines are especially impacted by this backlog, which significantly reduces their operational availability for missions in support of combatant commanders. The Committee directs the Secretary of the Navy to submit a report to the congressional defense committees not later than 90 days after the enactment of this Act that outlines a comprehensive, five-year submarine maintenance plan that restores submarine operational availability and fully utilizes both public and private nuclear-capable shipyards in accordance with all applicable laws. The plan should strive to provide both private and public shipyards with predictable frequency of maintenance availabilities and estimate any potential cost savings that distributing the workload may deliver. (Page 71) A March 2019 Navy report to Congress states that in response to the above committee report language, The Navy submitted an initial [submarine maintenance] plan in December 2018, that reflected FY 2019 budget information. The Navy has [now] updated this plan to incorporate data from the President's FY 2020 budget submitted on March 11, 2019…. … In the post-Cold War and post 9/11 era, there have been decades of decision making associated with the re-posturing of defense strategies, such as: the reduction in maintenance capacity and flexibility though Baes Realignment and Closures (BRAC), increased Operational Tempo (OPTEMPO), evolution of submarine life cycle maintenance plans, budget reductions, and budget uncertainties that have contributed to the current challenges facing the submarine fleet. The root cause of submarine idle time and associated loss of operational availability, as discussed in the recent Government Accountability Office (GAO) report 19-229, "Actions Needed to Address Costly Maintenance Delays Facing the Attack Submarine Fleet" (issued November 2018), is largely due to public shipyard capacity not keeping pace with growing maintenance requirements that have been building for a number of years prior to the USS BOISE (SSN 764) FY 2016 Engineered Overhaul (EOH). The workload to capacity mismatch resulted in lower priority attack submarine (SSN) availabilities (as compared to ballistic missile submarines and nuclear-powered aircraft carriers) being delivered late and a bow-waving of workload from one fiscal year to the next that could not be executed. The workload backlog exacerbated the public shipyard workload-to-capacity mismatch and contributed to an increasing trend in late SSN [maintenance] deliveries. The Navy has taken several actions to improve the workload-to-capacity balance at the public shipyards. Notably, over 20,600 workers were hired from FY 2013 through FY 2018, which after accounting for attrition, increased total end strength from 29,400 to 36,700. However, the accelerated hiring resulted in 56 percent of the production workforce having less than five years of experience. The less experienced workforce requires a greater investment in training, as described in the Navy's Report to Congress on the Naval Shipyard Development Plan (issued March 2018), which offers some near term productivity gains. The Navy has also taken additional actions to balance workload at our public shipyards by outsourcing four submarine maintenance availabilities to the private sector and plans to outsource another two submarine availabilities to the private shipyards starting in FY 2020 and FY 2021. Additionally, to ensure on-time delivery from maintenance availabilities, availability inductions have been rescheduled to occur when the shipyards have the capacity to accomplish the availability(s) within programmed schedule durations. This necessary action to improve the on-time delivery of current maintenance availabilities has resulted in some additional submarine maintenance backlog and some accumulation of idle time. Based on actions and initiatives the Navy is currently pursuing to improve submarine operational availability and the outsourcing of two additional submarine availabilities to the private sector, the Navy assesses that the submarine idle time will be eliminated by the end of FY 2023 and the submarine maintenance backlog will be worked off by the end of FY 2023. One issue for Congress is whether to approve, reject, or modify the Navy's FY2020 procurement and advance procurement (AP) funding requests for the Virginia-class program. In considering this issue, Congress may consider several factors, including the amount of work the Navy is proposing to fund for the program in FY2020 and whether the Navy has accurately priced the work it is proposing to do in FY2020. Another element of this issue concerns the funding profile for the third Virginia-class boat requested for procurement in FY2020. This issue is discussed separately in the next section. Another issue for Congress concerns the funding profile for the third Virginia-class boat that the Navy has requested for procurement in FY2020. As discussed earlier, Navy plans previously called for procuring two Virginia-class boats in FY2020. The third boat requested for FY2020 was added to the budget request as part of the FY2020 budget-planning cycle. The Navy states that since this third boat has not received any prior-year advance procurement (AP) funding, it would execute (i.e., be constructed) on a schedule similar to that of a boat procured in FY2023. The Navy is proposing to fully fund the procurement of the third boat in FY2020. As discussed in Appendix B , Congress in the past has fully funded the procurement of nuclear-powered ships (specifically, aircraft carriers) for which no prior-year AP funding had been provided. Given the anticipated schedule for executing a third Virginia-class boat procured in FY2020, one alternative funding profile for this boat would be to provide AP funding for the boat in FY2020-FY2022, followed by full funding (i.e., the remainder of the boat's procurement cost, in the form of regular procurement funding) for the boat in FY2023 (or perhaps AP funding in FY2020-FY2021, followed by full funding in FY2022). Supporters of providing only AP funding for the boat in FY2020 could argue that it would reduce FY2020 funding requirements for the Virginia-class program, which could make more FY2020 funding available for other programs, such as, for example, the LPD-17 Flight II amphibious ship program, the LHA-9 amphibious assault ship program, the Expeditionary Support Base (ESB) ship program, the Littoral Combat Ship (LCS) program, Navy aircraft or weapon acquisition programs, Navy maintenance and readiness initiatives, or other DOD programs. Supporters of fully funding a third Virginia-class boat in FY2020 could argue that it would reduce FY2021-FY2023 funding requirements for the Virginia-class program, which could make available more funding in those years for other programs, including most of those mentioned above, as well as the Virginia-class program itself (where it could, for example, support the procurement of a third Virginia-class boat in FY2022 and/or a third Virginia-class boat in FY2023). They could also argue that fully funding the procurement of a third Virginia-class boat in FY2020 would send a signal of resolve to potential adversaries such as China, particularly since it would make FY2020 the first year since FY1989 in which three SSNs were procured in a single year. Another potential issue for Congress concerns the potential industrial-base challenges of building both Columbia-class boats and Virginia-class attack submarines (SSNs) at the same time. Along with continued production of Virginia-class SSNs, the Navy in FY2021 is to also begin building Columbia-class ballistic missile submarines (SSBNs). Observers have expressed concern about the industrial base's capacity for building both Virginia- and Columbia-class boats without encountering bottlenecks or other production problems in one or both of these programs. Concerns about the ability of the submarine construction industrial base to execute an eventual procurement rate of two VPM-equipped Virginia-class boats and one Columbia-class boat per year have been heightened by recent reports of challenges faced by the two submarine-construction shipyards (GD/EB and HII/NNS), as well as submarine component supplier firms in meeting scheduled delivery times for Virginia-class boats as the Virginia-class program transitions over time from production of two "regular" Virginia-class boats per year to two VPM-equipped boats per year. Another potential issue for Congress concerns technical risk in the design for the Block V version of the Virginia-class program—the version being procured in FY2019-2023. A May 2019 GAO report—the 2019 edition of GAO's annual report surveying DOD major acquisition programs—stated the following regarding the Block V version of the Virginia-class design: Current Status In 2019, the Navy plans to award a multibillion dollar, multiyear contract for construction of 10 Block V submarines. Under the Navy's plan, all Block V ships will include acoustic superiority improvements, while the VPM will be added starting with the second Block V submarine. According to program officials, the design of Block V submarines will differ from Block IV by approximately 20 percent. Of this 20 percent, the program office considers 70 percent to constitute major changes. The program office plans to complete basic and functional designs for VPM by construction start—an approach consistent with best practices. However, the shipbuilder is currently behind schedule in completing detail design work, where (1) the design advances to the highest level of fidelity, (2) specific fabrication and installation instructions for the shipyard are developed, and (3) required production materials are identified. The program now plans to complete 76 percent of this work by construction start, compared to the 86 percent it initially planned, in part due to the shipbuilder's challenges in using a new design tool. Going forward, the Navy and shipbuilder will need to balance staffing levels for the remaining Block V design work with design efforts for the new Columbia class ballistic missile submarine. Construction of Block V and the Columbia class will coincide beginning in fiscal year 2021.This will require the Navy and its shipbuilder to manage staffing demands and other resources across both programs. In addition, program officials said vendor quality issues with welding on VPM have caused a 3.5-month delay in the schedule for the payload tubes for the first two submarines with VPM. The Navy plans to recover some time by accelerating tube manufacturing with a second vendor, but this approach may increase program costs. The Block V effort is subsumed under the SSN 774 major defense acquisition program, and is not managed as a separate program. In 2015, the Office of the Secretary of Defense shifted the program's oversight to the Navy. SSN 774 had already completed its required defense acquisition system milestone reviews before Block V started, but program officials said the Navy continues to conduct regular oversight of the Block V. Program Office Comments In commenting on a draft of this assessment, the program office provided technical comments, which we incorporated where appropriate. Another oversight issue for Congress concerns Virginia-class program issues raised in a January 2018 report from DOD's Director, Operational Test and Evaluation (DOT&E)—DOT&E's annual report for FY2017. Another issue for Congress concerns a problem with the hull coating used on Virginia-class boats that was reported in 2017. Another issue for Congress concerns three Virginia-class boats that were reported in 2016 to have been built with defective parts, and the operational and cost implications of this situation. Table 3 summarizes congressional action on the Navy's FY2020 funding request for the Virginia-class program. Appendix A. Past SSN Force-Level Goals This appendix summarizes attack submarine force-level goals since the Reagan Administration (1981-1989). The Reagan-era plan for a 600-ship Navy included an objective of achieving and maintaining a force of 100 SSNs. The George H. W. Bush Administration's proposed Base Force plan of 1991-1992 originally called for a Navy of more than 400 ships, including 80 SSNs. In 1992, however, the SSN goal was reduced to about 55 boats as a result of a 1992 Joint Staff force-level requirement study (updated in 1993) that called for a force of 51 to 67 SSNs, including 10 to 12 with Seawolf-level acoustic quieting, by the year 2012. The Clinton Administration, as part of its 1993 Bottom-Up Review (BUR) of U.S. defense policy, established a goal of maintaining a Navy of about 346 ships, including 45 to 55 SSNs. The Clinton Administration's 1997 QDR supported a requirement for a Navy of about 305 ships and established a tentative SSN force-level goal of 50 boats, "contingent on a reevaluation of peacetime operational requirements." The Clinton Administration later amended the SSN figure to 55 boats (and therefore a total of about 310 ships). The reevaluation called for in the 1997 QDR was carried out as part of a Joint Chiefs of Staff (JCS) study on future requirements for SSNs that was completed in December 1999. The study had three main conclusions: "that a force structure below 55 SSNs in the 2015 [time frame] and 62 [SSNs] in the 2025 time frame would leave the CINC's [the regional military commanders-in-chief] with insufficient capability to respond to urgent crucial demands without gapping other requirements of higher national interest. Additionally, this force structure [55 SSNs in 2015 and 62 in 2025] would be sufficient to meet the modeled war fighting requirements"; "that to counter the technologically pacing threat would require 18 Virginia class SSNs in the 2015 time frame"; and "that 68 SSNs in the 2015 [time frame] and 76 [SSNs] in the 2025 time frame would meet all of the CINCs' and national intelligence community's highest operational and collection requirements." The conclusions of the 1999 JCS study were mentioned in discussions of required SSN force levels, but the figures of 68 and 76 submarines were not translated into official DOD force-level goals. The George W. Bush Administration's report on the 2001 QDR revalidated the amended requirement from the 1997 QDR for a fleet of about 310 ships, including 55 SSNs. In revalidating this and other U.S. military force-structure goals, the report cautioned that as DOD's "transformation effort matures—and as it produces significantly higher output of military value from each element of the force—DOD will explore additional opportunities to restructure and reorganize the Armed Forces." DOD and the Navy conducted studies on undersea warfare requirements in 2003-2004. One of the Navy studies—an internal Navy study done in 2004—reportedly recommended reducing the attack submarine force level requirement to as few as 37 boats. The study reportedly recommended homeporting a total of nine attack submarines at Guam and using satellites and unmanned underwater vehicles (UUVs) to perform ISR missions now performed by attack submarines. In March 2005, the Navy submitted to Congress a report projecting Navy force levels out to FY2035. The report presented two alternatives for FY2035—a 260-ship fleet including 37 SSNs and 4 SSGNs, and a 325-ship fleet including 41 SSNs and 4 SSGNs. In May 2005, it was reported that a newly completed DOD study on attack submarine requirements called for maintaining a force of 45 to 50 boats. In February 2006, the Navy proposed to maintain in coming years a fleet of 313 ships, including 48 SSNs. Although the Navy's ship force-level goals have changed repeatedly in subsequent years, the figure of 48 SSNs remained unchanged until December 2016, when the Navy released a force-level objective for achieving and maintaining a force of 355 ships, including 66 SSNs. Appendix B. Options for Funding SSNs This appendix presents information on some alternative profiles for funding the procurement of SSNs. These alternatives include but are not necessarily limited to the following: two years of advance procurement (AP) funding followed by full funding —the traditional approach, under which there are two years of AP funding for the SSN's long-leadtime components, followed by the remainder of the boat's procurement funding in the year of procurement; one year of AP funding followed by full funding —one year of AP funding for the SSN's long-leadtime components, followed by the remainder of the boat's procurement funding in the year of procurement; full funding with no AP funding (single-year full funding , aka point-blank full funding ) —full funding of the SSN in the year of procurement, with no AP funding in prior years; incremental funding —partial funding of the SSN in the year of procurement, followed by one or more years of additional funding increments needed to complete the procurement cost of the ship; and advance appropriations —a form of full funding that can be viewed as a legislatively locked in form of incremental funding. Navy testimony to Congress in early 2007, when Congress was considering the FY2008 budget, suggested that two years of AP funding are required to fund the procurement of an SSN, and consequently that additional SSNs could not be procured until FY2010 at the earliest. This testimony understated Congress's options regarding the procurement of additional SSNs in the near term. Although SSNs are normally procured with two years of AP funding (which is used primarily for financing long-leadtime nuclear propulsion components), Congress can procure an SSN without prior-year AP funding, or with only one year of AP funding. Consequently, Congress at that time had the option of procuring an additional SSN in FY2009 and/or FY2010. Single-year full funding has been used in the past by Congress to procure nuclear-powered ships for which no prior-year AP funding had been provided. Specifically, Congress used single-year full funding in FY1980 to procure the nuclear-powered aircraft carrier CVN-71, and again in FY1988 to procure the CVNs 74 and 75. In the case of the FY1988 procurement, under the Administration's proposed FY1988 budget, CVNs 74 and 75 were to be procured in FY1990 and FY1993, respectively, and the FY1988 budget was to make the initial AP payment for CVN-74. Congress, in acting on the FY1988 budget, decided to accelerate the procurement of both ships to FY1988, and fully funded the two ships that year at a combined cost of $6.325 billion. The ships entered service in 1995 and 1998, respectively. The existence in both FY1980 and FY1988 of a spare set of Nimitz-class reactor components was not what made it possible for Congress to fund CVNs 71, 74, and 75 with single-year full funding; it simply permitted the ships to be built more quickly. What made it possible for Congress to fund the carriers with single-year full funding was Congress's constitutional authority to appropriate funding for that purpose. Procuring an SSN with one year of AP funding or no AP funding would not materially change the way the SSN would be built—the process would still encompass two or three years of advance work on long-leadtime components, and an additional five or six years or so of construction work on the ship itself. The outlay rate for the SSN could be slower, as outlays for construction of the ship itself would begin one or two years later than normal, and the interval between the recorded year of full funding and the year that the ship enters service would be longer than normal. Congress in the past has procured certain ships in the knowledge that those ships would not begin construction for some time and consequently would take longer to enter service than a ship of that kind would normally require. When Congress procured two nuclear-powered aircraft carriers (CVNs 72 and 73) in FY1983, and another two (CVNs 74 and 75) in FY1988, it did so in both cases in the knowledge that the second ship in each case would not begin construction until some time after the first. Appendix C. 2006 Navy Study on Options for Mitigating Projected Valley in SSN Force Level This appendix presents background information on a study initiated by the Navy in 2006 for mitigating the valley in the SSN force levels projected for the 2020s and 2030s. The study was completed in early 2007 and briefed to CRS and CBO on May 22, 2007. At the time of the study, the SSN force was projected to bottom out at 40 boats and then recover to 48 boats by the early 2030s. Principal points in the Navy study (which cite SSN force-level projections as understood at that time) include the following: The day-to-day requirement for deployed SSNs is 10.0, meaning that, on average, a total of 10 SSNs are to be deployed on a day-to-day basis. The peak projected wartime demand is about 35 SSNs deployed within a certain amount of time. This figure includes both the 10.0 SSNs that are to be deployed on a day-to-day basis and 25 additional SSNs surged from the United States within a certain amount of time. Reducing Virginia-class shipyard construction time to 60 months—something that the Navy already plans to do as part of its strategy for meeting the Virginia-class cost-reduction goal (see earlier discussion on cost-reduction goal)—will increase the size of the SSN force by two boats, so that the force would bottom out at 42 boats rather than 40. If, in addition to reducing Virginia-class shipyard construction time to 60 months, the Navy also lengthens the service lives of 16 existing SSNs by periods ranging from 3 months to 24 months (with many falling in the range of 9 to 15 months), this would increase the size of the SSN force by another two boats, so that the force would bottom out at 44 boats rather than 40 boats. The total cost of extending the lives of the 16 boats would be roughly $500 million in constant FY2005 dollars. The resulting force that bottoms out at 44 boats could meet the 10.0 requirement for day-to-day deployed SSNs throughout the 2020-2033 period if, as an additional option, about 40 SSN deployments occurring in the eight-year period 2025-2032 were lengthened from six months to seven months. These 40 or so lengthened deployments would represent about one-quarter of all the SSN deployments that would take place during the eight-year period. The resulting force that bottoms out at 44 boats could not meet the peak projected wartime demand of about 35 SSNs deployed within a certain amount of time. The force could generate a total deployment of 32 SSNs within the time in question—3 boats (or about 8.6%) less than the 35-boat figure. Lengthening SSN deployments from six months to seven months would not improve the force's ability to meet the peak projected wartime demand of about 35 SSNs deployed within a certain amount of time. To meet the 35-boat figure, an additional four SSNs beyond those planned by the Navy would need to be procured. Procuring four additional SSNs would permit the resulting 48-boat force to surge an additional three SSNs within the time in question, so that the force could meet the peak projected wartime demand of about 35 SSNs deployed within a certain amount of time. Procuring one to four additional SSNs could also reduce the number of seven-month deployments that would be required to meet the 10.0 requirement for day-to-day deployed SSNs during the period 2025-2032. Procuring one additional SSN would reduce the number of seven-month deployments during this period to about 29; procuring two additional SSNs would reduce it to about 17, procuring three additional SSNs would reduce it to about 7, and procuring four additional SSNs would reduce it to 2. The Navy added a number of caveats to these results, including but not limited to the following: The requirement for 10.0 SSNs deployed on a day-to-day basis is a current requirement that could change in the future. The peak projected wartime demand of about 35 SSNs deployed within a certain amount of time is an internal Navy figure that reflects recent analyses of potential future wartime requirements for SSNs. Subsequent analyses of this issue could result in a different figure. The identification of 19 SSNs as candidates for service life extension reflects current evaluations of the material condition of these boats and projected use rates for their nuclear fuel cores. If the material condition of these boats years from now turns out to be worse than the Navy currently projects, some of them might no longer be suitable for service life extension. In addition, if world conditions over the next several years require these submarines to use up their nuclear fuel cores more quickly than the Navy now projects, then the amounts of time that their service lives might be extended could be reduced partially, to zero, or to less than zero (i.e., the service lives of the boats, rather than being extended, might need to be shortened). The analysis does not take into account potential rare events, such as accidents, that might force the removal of an SSN from service before the end of its expected service life. Seven-month deployments might affect retention rates for submarine personnel.

Summary: The Navy has been procuring Virginia (SSN-774) class nuclear-powered attack submarines (SSNs) since FY1998. The three Virginia-class boats that the Navy has requested for procurement in FY2020 would be the 31st, 32nd, and 33rd boats in the class. Virginia-class submarines are being procured under a multiyear procurement (MYP) contract covering at least 10 boats to be procured in FY2019-FY2023. Navy plans previously called for procuring two Virginia-class boats in FY2020. The third boat requested for FY2020 was added to the budget request as part of the FY2020 budget-planning cycle. The Navy states that since this third boat has not received any prior-year advance procurement (AP) funding, it would execute (i.e., be constructed) on a schedule similar to that of a boat procured in FY2023. The Navy plans to build the second of the two boats procured in FY2019, the second and third boats requested for procurement in FY2020, the second of the two boats planned for procurement in FY2021, and all subsequent Virginia-class boats with the Virginia Payload Module (VPM), an additional, 84-foot-long, mid-body section equipped with four large-diameter, vertical launch tubes for storing and launching additional Tomahawk missiles or other payloads. The Navy's FY2020 budget submission shows that Virginia-class boats with and without the VPM have estimated recurring unit procurement costs of roughly $3.2 billion and $2.8 billion, respectively. The Navy estimates the combined procurement cost of the three Virginia-class boats requested for procurement in FY2020 at $9.274.4 (i.e., about $9.3 billion). The boats have received $1,756.9 million in prior-year "regular" advance procurement (AP) funding and $361.6 million in additional Economic Order Quantity (EOQ) AP funding for components of boats being procured under the FY2019-FY2023 MYP contract. The Navy's proposed FY2020 budget requests the remaining $7,155.9 million in procurement funding needed to complete the boats' estimated combined procurement cost, as well as $1,887.6 million in "regular" AP funding for Virginia-class boats to be procured in future fiscal years and $882.0 million in additional EOQ AP funding for components of boats to be procured under the FY2019-FY2023 MYP contract, bringing the total amount of procurement and AP funding requested for the program in FY2020 to $9,925.5 million (i.e., about $9.9 billion), excluding outfitting and post-delivery costs. The Navy's SSN force included 51 boats at the end of FY2018. The Navy's force-level goal for SSNs is to achieve and maintain a force of 66 boats. From the mid-2020s through the early 2030s, the number of SSNs is projected to experience a valley or trough, reaching a minimum of 42 boats in FY2027-FY2028. Some observers are concerned that this projected valley—a consequence of having procured a relatively small number of SSNs during the 1990s, in the early years of the post-Cold War era—could lead to a period of heightened operational strain for the SSN force, and perhaps a period of weakened conventional deterrence against potential adversaries such as China. The projected SSN valley was first identified by CRS in 1995 and has been discussed in CRS reports and testimony every year since then. The Navy's 30-year shipbuilding plan projects that, after reaching its projected 42-boat minimum, the SSN force will increase to 66 boats by FY2048. Issues for Congress regarding the Virginia-class program include whether to approve, reject, or modify the Navy's FY2020 procurement and advance procurement (AP) funding requests for the Virginia-class program; the funding profile for the third Virginia-class boat requested for procurement in FY2020; the potential industrial-base challenges of building both Columbia-class boats and Virginia-class attack submarines (SSNs) at the same time; and technical risk in the design for the Block V version of the Virginia-class program.