February 14, 2017 – “Nuclear weapons have been a cornerstone of U.S. national security since they were developed during World War II. In the Cold War, nuclear forces were central to U.S. defense policy, resulting in the buildup of a large arsenal. Since that time, nuclear forces have figured less prominently than conventional forces, and the United States has not built any new nuclear weapons or delivery systems for many years. The nation’s current nuclear forces are reaching the end of their service life. Those forces consist of submarines that launch ballistic missiles (SSBNs), land-based intercontinental ballistic missiles (ICBMs), long-range bomber aircraft, shorter-range tactical aircraft, and the nuclear weapons that those delivery systems carry. Over the next two decades, essentially all of those nuclear delivery systems and weapons would have to be refurbished or replaced with new systems to continue operating. Consequently, the Congress will need to make decisions about what nuclear forces the United States should field in the future and thus about the extent to which the nation will pursue nuclear modernization plans. To help the Congress make those decisions, the National Defense Authorization Act for Fiscal Year 2013 required CBO to estimate the 10-year costs to operate, maintain, and modernize U.S. nuclear forces. In response, CBO published Projected Costs of U.S. Nuclear Forces, 2014 to 2023. The National Defense Authorization Act for Fiscal Year 2015 requires CBO to update its estimate of the cost of nuclear forces every two years. This report is the second such update. If carried out, the plans for nuclear forces delineated in the Department of Defense’s (DoD’s) and the Department of Energy’s (DOE’s) budget requests for fiscal year 2017 would cost a total of $400 billion over the 2017–2026 period, CBO estimates—an average of $40 billion a year. (In this analysis, “costs” refers to budget authority, the amount that would need to be appropriated to implement the plans.) The current 10-year total is 15 percent higher than CBO’s most recent previous estimate of the 10-year costs of nuclear forces, $348 billion over the 2015–2024 period. Both the current and previous 10-year estimates are presented in nominal dollars, meaning that they include the effects of inflation. Besides presenting an estimate of those costs, this report also describes the major differences between CBO’s current estimate and its most recent previous estimate, which was published in January 2015. Most of the increase in the total estimated cost of nuclear forces reflects the fact that the current estimate spans a 10-year period that begins and ends two years later than the 2015 estimate and thus includes two later years of development in nuclear modernization programs. The development costs of weapon systems typically increase as a program proceeds, which means that the current estimate replaces two lower-cost years with two higher-cost years. The current estimate also includes the initial years of purchases in some programs that were not covered by the previous estimate, further raising costs in the 2017–2026 period relative to the 2015–2024 period. In addition, in the two years since CBO’s earlier estimate, the modernization plans for some nuclear systems have become better defined, leading to higher cost projections for some programs and lower projections for others.”