"The most expensive component is the space-based interceptor layer, which accounts for about 70 percent of acquisition costs and 60 percent of total costs," the Congressional Budget Office wrote in a new analysis of a notional national missile defense system.
Congressional Budget Office estimate: $1.2 trillion over 20 years
The CBO concluded a notional national missile defense (NMD) architecture consistent with President Donald Trump’s January 2025 executive order could cost up to $1.2 trillion to develop, deploy and operate for 20 years. Most of that—more than $1 trillion—would be acquisition spending, the office said, encompassing the system’s major components, notably the interceptor layers and a space-based missile warning and tracking system.
Because the Department of Defense has publicly released few details about the architecture the Pentagon actually plans, the CBO said it was "impossible to estimate the long-term cost of the GDA [Golden Dome for America] system being contemplated by DoD." Instead, the office modeled a notional system based on the capabilities called for in the executive order and on defensive systems that would be required to meet that objective.
What the modeled system could — and could not — do
Under the CBO’s notional architecture, the system would "have the capacity to fully engage an attack mounted by a regional adversary (that is, one with limited capabilities, such as North Korea) or a small-scale attack mounted by a peer or near-peer adversary (one with military capabilities similar to those of the United States, namely Russia or China)." The report explicitly warns that the same system "could be overwhelmed by a full-scale attack mounted by a peer or near-peer adversary."
The CBO also emphasized a distinction that may be familiar to planners: "'fully engage' is not the same as 'fully defeat' because no defense works perfectly every time," the report says.
Space-based interceptors: cost driver and conditional choice
CBO identified the space-based interceptor layer as the dominant driver of acquisition cost. The estimated 70 percent share of acquisition spending and 60 percent of total program costs places that layer at the center of the budget question. Acquisition costs, the CBO noted, also include a space-based missile warning and tracking capability.
Gen. Michael Guetlein, the Golden Dome program manager, told lawmakers in April that the Pentagon would not pursue space-based interceptors for boost-phase interception if the approach proved "not affordable and scalable." Guetlein said, "If boost-phase intercept from space is not affordable and scalable, we will not produce it," adding, "We are so focused on affordability. If we cannot do it affordab[ly], we will not go into production."
DoD tallies, public remarks and the Pentagon response
The CBO estimate sits well above earlier public figures. In May 2025, President Donald Trump said the program would cost $175 billion, a figure presented as a presumptive initial deployment cost. In congressional testimony last month, Gen. Guetlein estimated the cost to stand up Golden Dome at roughly $185 billion.
The CBO said those DoD figures "appear to be in line with budget projections," but added that the department’s stated cost appears to cover a shorter time frame and may reflect a different scope of activities and budget categories. A Pentagon spokesperson declined to comment for the CBO report beyond pointing to Guetlein’s April testimony, in which he disputed outside estimates. Guetlein argued that prior public calculations were "not estimating what I’m building" and were based on multiplying legacy-system costs rather than the different acquisition authorities, strategies and efficiency measures he said Golden Dome will use.
What this means for the Department of Defense, lawmakers, and taxpayers
- Department of Defense and Golden Dome managers: Budget choices on whether to include space-based boost-phase interceptors will be a central program decision; Guetlein framed that choice in affordability and scalability terms.
- Congress and budget overseers: The divergence between a 20-year CBO estimate and shorter-horizon DoD figures points to a need to reconcile time frames and scopes when assessing authorization and appropriations requests.
- U.S. taxpayers and the public: The CBO’s $1.2 trillion projection places long-term acquisition and sustainment costs at the forefront of public debate over the program’s scale and trade-offs.
The CBO’s analysis makes clear that the final fiscal profile of Golden Dome—or the Golden Dome for America architecture the Pentagon may pursue—depends on concrete design choices that the Defense Department has not publicly released. Those choices, particularly about space-based interceptors, will determine whether the program stays closer to the lower, shorter-term figures cited publicly or to the multidecade costs CBO modeled. The next decisions and disclosures about architecture and time horizon will shape both budget planning and congressional scrutiny.
