Discretionary Spending

Function 050 - National Defense

Cancel the Ground-Based Midcourse Defense System

CBO periodically issues a compendium of policy options (called Options for Reducing the Deficit) covering a broad range of issues, as well as separate reports that include options for changing federal tax and spending policies in particular areas. This option appears in one of those publications. The options are derived from many sources and reflect a range of possibilities. For each option, CBO presents an estimate of its effects on the budget but makes no recommendations. Inclusion or exclusion of any particular option does not imply an endorsement or rejection by CBO.

Billions of Dollars 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2019-
Change in Spending  
  Budget authority 0 -2.5 -2.2 -1.8 -1.8 -1.9 -2.3 -2.5 -2.5 -2.6 -8.4 -20.3
  Outlays 0 -1.0 -1.9 -2.0 -1.9 -1.9 -2.0 -2.2 -2.4 -2.5 -6.8 -17.7

This option would take effect in October 2019.


The Ground-Based Midcourse Defense (GMD) system is designed to defend against intermediate and long-range missiles during the middle portion of their trajectory. It uses interceptor missiles to launch a kill vehicle, which uses onboard sensors to locate the threat and then maneuvers to hit and kill it. The system is part of a layered defense that combines sensors, control systems, and several types of interceptors or other methods to destroy attacking missiles of various ranges and during different portions of their trajectories.

GMD comprises 44 interceptor missiles in silos at Fort Greely, Alaska, and Vandenberg Air Force Base, California; battle management command-and-control software; and a communications system to relay information to and from the interceptors in flight. The Department of Defense (DoD) is planning to add 20 interceptors to the system and has several programs under way to support GMD testing and improve the GMD system.


This option would cancel the GMD system and its support efforts, including the Improved Homeland Defense Interceptors, Common Kill Vehicle, and Multi-Object Kill Vehicle programs. The option would not affect the overarching command-and-control or sensor programs that support other missile defense systems.

Effects on the Budget

This option would reduce budget authority by about $20 billion over the next decade, the Congressional Budget Office estimates. Outlays would decrease by a smaller amount—about $18 billion over that period—because the budget authority provided would not be spent right away as development of new systems requires extensive research and planning. Those savings would result from ending efforts to improve the interceptors and kill vehicles, canceling procurement of additional interceptors, and avoiding the costs of operation and maintenance of the GMD system. The estimate of savings does not include reductions in the number of military personnel because the GMD site at Fort Greely is operated by Army National Guard units, which CBO assumes would be assigned to other activities.

CBO's estimate of savings is based on plans as described in DoD's budget documentation. Those estimates, which CBO has projected to 2028, are somewhat uncertain because technology development programs historically have experienced cost growth relative to DoD's estimates. Some of the programs that this option would cancel are intended to fix problems with the existing interceptors or kill vehicles, and those problems could prove more difficult (and expensive) to overcome than DoD or CBO has anticipated.

CBO's estimate of savings is based on the full cancellation of GMD and of the supporting programs designed to improve performance. If DoD chose instead to continue fielding the GMD system but to reduce the number of interceptors, savings would be substantially less and would not be proportional to the reduction in the number of interceptors fielded. That is because the development programs that are intended to improve performance, which constitute about half of the estimated costs over the next decade, would still continue. In addition, fixed costs associated with maintaining each base and continuing to operate at least one interceptor there would result in savings in operations costs for GMD that would be less than proportional to the reduction in the number of interceptors.

Other Effects

One argument for this option is the GMD program's mixed track record. Critics argue that initial development of the system was rushed, resulting in quality control and design flaws. They contend that GMD has failed in six of 10 intercept tests since its deployment in 2004 (although interpretation of whether several of those tests succeeded or failed is controversial). Furthermore, critics argue that even if the system performed as designed, it could be defeated by decoys or other countermeasures. U.S. nuclear forces are sufficient to deter any attacks on the United States, in their view. A second argument is that the system has been a source of geopolitical tension. The United States withdrew from the Anti-Ballistic Missile Treaty, a bilateral agreement with Russia, before deployment of GMD. Since that withdrawal, the Russians have repeatedly protested against U.S. missile defenses. Some analysts attribute recent Russian improvements to their nuclear forces to concerns about U.S. missile defenses. A final argument is that DoD could use other programs to perform some of the missions designated for GMD. For example, the Aegis missile defense system now deployed on Navy ships and at one location ashore also intercepts missiles in the midcourse phase of their flight and is slated to be tested against long-range threats. In addition, DoD is devising defenses that would destroy missiles during their boost phase (while their rocket boosters are still firing), which could defend against some of the threats that GMD is intended to address. However, if DoD chose to increase funding for those programs to compensate for the loss of GMD, the net savings for this option would decline accordingly.

An argument against this option is the current threat posed by ballistic missile launches from hostile nations. Despite the deterrence against attack provided by the large U.S. nuclear arsenal, the threat has increased recently, in particular with the successful testing of long-range missiles by North Korea. Advocates of the GMD system contend that the continued operation, expansion, and improvement of GMD would provide urgently needed protection for the United States and its allies.