In April 2017, we issued our latest report on NNSA’s 25-year plans to modernize the nation’s nuclear weapons stockpile and its supporting infrastructure. In this report, we identified two areas of misalignment between NNSA’s modernization plans and the estimated budgetary resources needed to carry out those plans, which could result in challenges to NNSA in affording its planned portfolio of modernization programs. First, we found that NNSA’s estimates of funding needed for its modernization plans sometimes exceeded the budgetary projections included in the President’s planned near- and long-term modernization budgets. In the near-term (fiscal years 2018 through 2021), we found that NNSA may have to defer certain modernization work beyond that time period in order to execute its program within the planned budget, which could increase modernization costs and schedule risks. This is a pattern we have previously identified as a “bow wave”—an increase in future years’ estimated budget needs that occurs when agencies are undertaking more programs than their resources can support. In the long- term (fiscal years 2022 through 2026), we found that NNSA’s modernization program budget estimates sometimes exceeded the projected budgetary resources planned for inclusion in the President’s budget, raising additional questions about whether NNSA will be able to afford the scope of its modernization program. Second, the costs of some major modernization programs—such as for nuclear weapon refurbishments—may also increase and further strain future modernization budgets. As we reported in April 2017, NNSA estimates of funding needed for its modernization plans sometimes exceeded the budgetary projections included in the President’s planned near- and long-term modernization budgets. We found that NNSA may have to defer certain modernization work planned for fiscal years 2018 through 2021 beyond its current 5-year planning period, called the Future-Years Nuclear Security Program (FYNSP). As we reported in April 2017, this is caused by a misalignment between NNSA’s budget estimates for certain nuclear modernization programs and the President’s budgets for that period. We concluded that this deferral could exacerbate a significant bow wave of modernization funding needs that NNSA projects for the out-years beyond the FYNSP and could potentially increase modernization costs and schedule risks. As we have previously reported, such bow waves occur when agencies defer costs of their programs to the future, beyond their programming periods, and they often occur when agencies are undertaking more programs than their resources can support. As NNSA’s fiscal year 2017 budget materials show, its modernization budget estimates for fiscal years 2022 through 2026—the first 5 years beyond the FYNSP—may require significant funding increases. For example, in fiscal year 2022, NNSA’s estimates of its modernization budget needs are projected to rise about 7 percent compared with the budget estimates for fiscal year 2021, the last year of the FYNSP, as shown in figure 1. The analysis in our April 2017 report showed that NNSA has shifted this modernization bow wave to the period beyond the FYNSP time frame in each of the past four versions of the annual Stockpile Stewardship and Management Plan. For example, in the Fiscal Year 2014 Stockpile Stewardship and Management Plan, NNSA’s budget estimates for its modernization programs increased from a total of about $9.3 billion in fiscal year 2018, the last year of the FYNSP, to about $10.5 billion in fiscal year 2019, the first year after the FYNSP—an increase of about 13 percent. Similar patterns showing a jump in funding needs immediately after the last year of the FYNSP are repeated in the funding profiles contained in the fiscal year 2015, 2016, and 2017 plans. As we have previously reported, deferring more work to future years can increase cost and schedule risks and can put programs in the position of potentially facing a backlog of deferred work that grows beyond what can be accommodated in future years. The Fiscal Year 2017 Stockpile Stewardship and Management Plan shows that NNSA’s overall modernization budget estimates for fiscal years 2022 through 2026—the out-years beyond the FYNSP—may exceed the projected funding levels in the President’s budgets for that time period, raising further questions about the affordability of NNSA’s nuclear modernization plans. According to NNSA’s data, the agency’s estimated budget needed to support modernization totals about $58.4 billion for fiscal years 2022 through 2026, and the out-year funding projections contained in the President’s fiscal year 2017 budget for the same period total about $55.5 billion. The President’s out-year funding projections, therefore, are approximately $2.9 billion, or about 5.2 percent, less than NNSA estimates it will need over the same time period. Despite this potential shortfall, NNSA’s Fiscal Year 2017 Stockpile Stewardship and Management Plan concludes that the modernization program is generally affordable in the years beyond the FYNSP for two reasons. First, the President’s out-year funding projections are sufficient to support NNSA’s low-range cost estimates for its modernization programs for fiscal years 2022 through 2026. Based on NNSA data, the low-range cost estimates for fiscal years 2022 through 2026 total approximately $54.4 billion and the President’s out-year funding projections total about $55.5 billion. Figure 2 illustrates data from the 2017 plan showing NNSA’s nominal budget estimates, including high- and low-range cost estimates for its modernization program, along with the out-year funding projections from the President’s fiscal year 2017 budget, for fiscal years 2022 to 2026. Second, NNSA concludes that its modernization programs are generally affordable beyond the FYNSP because the agency’s estimated modernization budget needs will begin to decrease in fiscal year 2027. In our April 2017 report, we noted that NNSA’s conclusion—that its modernization program is affordable because the President’s out-year funding projections fall within NNSA’s modernization cost ranges—is overly optimistic. This is because NNSA’s conclusion is predicated on optimistic assumptions regarding the cost of the modernization program beyond the FYNSP, particularly for fiscal years 2022 through 2026. For the program to be affordable, NNSA’s modernization programs would need to be collectively executed at the low end of their estimated cost ranges. The plan does not discuss any options NNSA would pursue to support or modify its modernization program if costs exceeded its low- range cost estimates. In addition, the Fiscal Year 2017 Stockpile Stewardship and Management Plan states that the nominal cost of NNSA’s modernization program is expected to decrease by approximately $1 billion in fiscal year 2027. In that year, according to the 2017 plan, it is anticipated that NNSA’s estimated budgets for its modernization program will begin to fall in line with projections of future presidential budgets. However, as we noted in our April 2017 report, the decrease that NNSA anticipates in its modernization funding needs beginning in fiscal year 2027 may not be achievable if the projected mismatch between NNSA’s estimates of its modernization budget needs and the projections of the President’s modernization budget for fiscal years 2022 through 2026 is not resolved. This mismatch creates concerns that NNSA will not be able to afford planned modernization costs during fiscal years 2022 through 2026 and will be forced to defer them to fiscal year 2027 and beyond, continuing the bow wave patterns discussed above. Our April 2017 report identified misalignment between NNSA’s estimate of its budget needs and NNSA’s internal cost range estimates for several of its major modernization programs. Further, we found that the costs of some major life extension programs (LEPs) may increase in the future, which may further strain NNSA’s planned modernization budgets. With respect to the alignment of NNSA’s estimate of its budget needs and NNSA’s internal cost range estimates, we found that NNSA’s budget estimates were generally consistent with NNSA’s high- and low-range cost estimates. However, for some years, NNSA’s low-range cost estimates exceeded the budget estimates for some of the programs, suggesting the potential for a funding shortfall for those programs in those years. Specifically, we found that the low-range cost estimates for the W88 Alteration 370 program and all LEPs discussed in our April 2017 report exceeded their budget estimates for some fiscal years within the 10-year time period from fiscal year 2017 to 2026. As we reported in the 2013 and 2016, this misalignment indicates that NNSA’s estimated budgets may not be sufficient to fully execute program plans and that NNSA may need to increase funding for these programs in the future. Additionally, we found that the costs of two ongoing nuclear weapon LEPs and the W88 Alteration 370 program may increase in the future, based on NNSA information that was produced after the release of the fiscal year 2017 budget materials. These potential cost increases could further challenge the extent to which NNSA’s budget estimates support the scope of modernization efforts. The LEPs facing potential cost increases include: B61-12 LEP. An independent cost estimate for the program completed in October 2016 exceeded the program’s self-conducted cost estimate (conducted in June 2016) by $2.6 billion. We are conducting ongoing work to determine how NNSA has, if at all, reconciled this difference. W80-4 LEP. Officials from NNSA’s Office of Cost Policy and Analysis told us that this program may be underfunded by at least $1 billion to meet the program’s existing schedule. W88 Alteration 370.