Another reason to cancel the Sentinel missile: the rising cost of its nuclear warhead

As widely reported, the estimated cost for the Air Force’s new Sentinel intercontinental ballistic missile recently rose dramatically, by 37 percent, to a total of almost $132 billion. This cost increase represents a breach of what is known as the Nunn-McCurdy Act, mandating an evaluation by the Pentagon of whether to go forward with the program. Less well known is that the effort to build new nuclear warheads, including one for the Sentinel missile, is also likely to cost far more than previously projected, with a critical element of the project potentially costing more than double earlier estimates.

Buried deep in the Energy Department’s  Fiscal Year 2025 budget request is a new ballpark cost for a proposed production plant to make plutonium “pits,” the explosive core of nuclear weapons. The estimate for the plant rose dramatically, from $6.9-11.1 billion to $18-25 billion, an increase of up to 260 percent. On top of that, the budget request says the construction schedule–already years behind the initial goal–is expected to be delayed by another 1-3 years.

New plutonium pits are used to make new nuclear weapons, something the United States has not done since the early 1990s, when the Cold War ended. Congress has mandated that the United States make a minimum of 80 pits per year by 2030. That task falls to the National Nuclear Security Administration, the semi-autonomous agency in the Energy Department responsible for developing, maintaining and now manufacturing US nuclear weapons. Its leader, Jill Hruby, testified back in 2021 that the agency would not make the 2030 deadline, missing it by between two and five years.

Fast forward three years. Last month Hruby testified before Congress that the agency’s plan now has the NNSA producing 80 pits per year no earlier than 2035, a full five years past the initial deadline.

However, Congressional staff and other government sources I have talked to say 2040 is a more realistic estimate. The NNSA still does not have a comprehensive schedule or cost estimate for the project, even though the agency started working on one in 2018. In 2021, Congress mandated NNSA produce a comprehensive schedule as soon as possible. NNSA is now saying it will have that schedule and full cost estimate in April of 2026, eight years after starting work on it, five years after Congress demanded it, and four years before the 2030 production target. Despite having no schedule or cost estimate, the NNSA asks Congress for $2.8 billion annually for the effort–and Congress has frequently given even more than the agency requested.

On the spending side, in another recent forum, Hruby gave a new rough total cost for the pit production project, which includes manufacturing work at Los Alamos National Laboratory in addition to the vastly over-budget plant that is planned for the Savannah River Site in South Carolina. She put the total cost at up to $37 billion—though again, that is not the formal estimate, which won’t come until 2026.

A final element must be added to the equation to understand the total costs of the Sentinel missile and its warhead. Specifically, the pit production costs do not include the money that must be spent to make the rest of the new nuclear weapon into which the pit will go. Known as the W87-1 warhead, it is the first all-new nuclear weapon since the end of the Cold War. That warhead is currently estimated to cost more than $12 billion.

However, one should always take NNSA estimates with a grain—or two—of salt. As an independent assessment of the agency’s pit production plan showed, the agency’s major projects consistently cost far more and take far longer than official cost estimates reflect. In just one example, the Uranium Processing Facility in Oak Ridge, Tenn., was initially projected at under $2 billion, then rose to $6.5 billion even though the scope was reduced, and is now over $8 billion and being rebaselined.

In short, the total cost of the Sentinel missile, when you include all the costs of the warhead it will carry, will be more than $180 billion. And, based on precedent, that estimate is probably too low and isn’t even an official estimate for the new pits that will go in the new warheads. Add the delays that will put pit production as much as a decade behind schedule, and you have an extraordinarily expensive train wreck.

The mandatory evaluation that the Sentinel missile is currently undergoing is required to consider whether the program should be cancelled. The Union of Concerned Scientists has already made the case that ICBMs are not only extraneous but in fact unnecessarily increase risk to the country, and thus should be eliminated. The rising costs of both the Sentinel acquisition program and the warhead it will carry only make that case stronger.