www.cbo.gov
CONGRESSIONAL BUDGET OFFICE Phillip L. Swagel, Director
U.S. Congress
Washington, DC 20515
May 5, 2025
Honorable Deb Fischer Honorable Angus S. King Jr.
Chair Ranking Member
Subcommittee on Strategic Forces Subcommittee on Strategic Forces
Committee on Armed Services Committee on Armed Services
United States Senate United States Senate
Washington, DC 20510 Washington, DC 20510
Re: Effects of Lower Launch Costs on Previous Estimates for Space-Based,
Boost-Phase Missile Defense
Dear Senators:
As you requested, this letter provides the Congressional Budget Office’s
estimates of how recent declines in the costs of launch services would
change previous estimates of the costs to deploy a constellation of space-
based interceptors (SBIs) designed to defeat one or two intercontinental
ballistic missiles (ICBMs) fired at the United States by a regional
adversary, such as North Korea. Those previous estimates appeared in
studies published by CBO in 2004 and by the National Research Council
(NRC) in 2012.
1
Although launch costs are lower now, threats and U.S.
policies have changed since those studies were published in ways that could
increase the overall size and cost of an SBI constellation.
By themselves, decreases in launch costs could reduce the previous
estimates of the 20-year costs of various SBI constellations by 30 percent to
40 percent, CBO finds. For the lowest-cost alternative that CBO examines
here, the reduction in launch costs would cause the total estimated cost of
deploying and operating the SBI constellation for 20 years to fall from
$264 billion to $161 billion (in 2025 dollars). For the highest-cost
1
Congressional Budget Office, Alternatives for Boost-Phase Missile Defense (July 2004),
www.cbo.gov/publication/15852; and National Research Council, Making Sense of Ballistic
Missile Defense: An Assessment of Concepts and Systems for U.S. Boost-Phase Missile
Defense in Comparison to Other Alternatives (National Academies Press, 2012),
https://doi.org/10.17226/13189.
